After more than two decades of searching, scientists have finally observed a phenomenon in a hot and dense particle 'soup' similar to that which filled the cosmos moments after the Big Bang. The observation could help cosmologists better understand the incredibly hot and dense state of the universe in its earliest moments.

The world's most powerful particle accelerator, the Large Hadron Collider (LHC), regularly creates this so-called quark-gluon plasma by smashing together the atomic nuclei of heavy elements like lead and generating sprays of particles called jets, from which this hot and dense particle soup emerges. This is necessary because in the modern universe, quarks and gluons, referred to as "partons," are only ever found together comprising particles like protons and neutrons. Thus, it takes the kind of energy generated by smashing atoms together at near-light-speeds to free these partons and generate the hot 'soup' known as quark-gluon plasma.

As particles ripple through the quark-gluon plasma, they lose energy and momentum to this medium, which should create wakes in this primordial soup, much like that which is created when the hull of a boat pushes through the ocean. However, researchers had failed to see this so-called "diffusion wake" for two decades. That is, until now.

"Observing and quantifying the quark-gluon plasma diffusion wake opens the door to the new precision characterization of the properties and dynamics of the quark-gluon plasma, and promises new insights into the evolution of the early universe,” team leader Raghunath Pradhan of the University of Illinois Chicago (UIC) said in a statement.

A new approach in the hunt for particle wakes

Previously, the search for wave signals had involved generating events involving the production of a jet alongside a particle called a Z boson. However, while this had provided some evidence of particle wakes, signals from these wakes are subtle and easily drowned out by other jet-related effects, meaning these detections weren't statistically significant enough to be classed as a confirmed detection.

To search for the wave signal, this team took a different approach and used the LHC to smash together two lead nuclei to create jets of particles that were back-to-back, called a dijet event. The unique shape of these events meant that signals from wakes could be more easily disentangled from surrounding noise.

The team's measurement showed a clear lack of particles behind the direction of the jets, which was particularly prominent at relatively low momentum. That is exactly what would be expected for a diffusion wake. The strongest wake signals were detected in more centralised lead-lead collisions, which create more quark-gluon plasma.

"This observation is a culmination of a decades-long quest to observe the wake phenomenon; it has been predicted by theory over 20 years ago, but remained elusive in the experimental data," team leader Olga Evdokimov of UIC said.

The team's research was accepted for publication on June 25 in the journal Physical Review Letters.

Is the Milky Way even bigger than we thought? New observations have revealed that our galaxy's spiral arms could stretch farther and wider than we previously concluded.

The Milky Way's spiral structure was discovered over 175 years ago in 1850. But new information could completely change our understanding of our cosmic home. Astronomers have taken a new look at our Milky Way galaxy using data from NASA's Chandra X-ray observatory and the European Space Agency's XMM-Newton observatory and have pieced together new, precise measurements of the galaxy's spiral arms. And what they found is that its spiral arms stretch out farther than we once thought, a discovery that could change our understanding of our galaxy's structure.

"The differences are small, but any revision of these distances is important because they are so fundamental for understanding our galaxy," co-author Ilaria Fornasiero said in a statement. "For example, this could mean that astronomers have to revise estimates of the mass of the galaxy, because that affects how wide the arms stretch."

To make this new galactic measurement, researchers had to get a little creative with the data. They measured these cosmic distances by observing X-ray light scattered by the dust in the Milky Way's arms as it echoed out from around gamma-ray bursts, or the most powerful explosions across the universe that happen either when massive stars collapse or neutron stars collide and merge. These massive bursts of energy are happening far beyond our galaxy, but their X-ray light is so powerful that it can reach and bounce off of dust clouds in the Milky Way's arms.

By studying the diameters of the rings of light as they expand away from these explosions and observing how and where they reflect off of the Milky Way's dust, the team was able to precisely point to where the galaxy's arms extend.

"This is a very direct way – relying only on geometry – to precisely measure distances to the Milky Way's spiral arms," lead author Beatrice Vaia, who led this research as a PhD student, said in the statement. "Most other methods rely on assumptions about how the Milky Way rotates, which become increasingly uncertain in the outer regions of our galaxy."

The team used the X-ray light from three different gamma-ray bursts to look at three of the Milky Way's spiral arms: the Perseus, the Outer, and the Outer-Scutum-Centaurus arms. According to these new measurements, both the Outer and the Outer Scutum-Centaurus arms are about ten percent more distant than was previously thought.

With this data, the team was also able to measure the thickness of the Milky Way's most distant arm, which they found to be about 3,500 light-years wide. By incorporating the arm's width, the team ensured that they were measuring the full extension of the arm and not just one particular dust cloud, further bolstering their findings.

While it's interesting that the Milky Way's arms extend out a bit farther and wider than we previously thought, these new findings could have larger implications. Based on these new measurements, astronomers may have to reinvestigate our understanding of our galaxy's mass distribution, rotation and overall structure. This evolving understanding could ripple out and impact how we view not just the structure but the evolution of our galaxy and beyond.

But this study isn't one that can be replicated too easily. That's because gamma-ray bursts don't happen all of the time. Even more rare are bursts that we can see clearly through our galaxy.

"We’re relying on the universe to provide us with these events, and so far, over 25 years, we’ve only found a handful that we can use," co-author Andrea Tiengo of Scuola Universitaria Superiore IUSS Pavia said in the same statement. "That said, we will continue to be on the lookout for more."

This work was described in a new study published June 19 in the journal Astronomy & Astrophysics.

Astronomers have traced a high-energy "ghost particle" back to Shadow Blaster, a star-forming galaxy located 11 billion light-years away. That means that this particle, a neutrino, had been travelling to us ever since the 13.8 billion year-old universe was just around 3 billion years old.

The discovery offers the first evidence that star-forming galaxies like Shadow Blaster play a significant role in populating the universe with mysterious high-energy cosmic ghost-neutrinos. These particles get their spooky nickname because, possessing virtually no mass and no electric charge, they pass through matter with little to no interaction while moving at nearly the speed of light. For context, as you read the preceding sentence, over 65 billion neutrinos streamed through every square inch of your body; that's about 100 billion per square centimeter.

Despite the difficulty associated with detecting such particles, humanity has been spotting neutrinos since the 1960s, but only a few sources of these particles have been identified. Neutrinos are the second most abundant particles in the cosmos after photons, particles of light, and the identified sources are nowhere near enough to account for this abundance. That has prompted the search for other, hidden neutrino sources, especially those which can accelerate neutrinos to high energies. Now that hunt has led to the identification of the incredibly bright Shadow Blaster galaxy, officially designated JCMT0402−0424, which shines in infrared, as a potential neutrino source.

"Shadow Blaster possesses the kind of dense, gas-rich environment that theoretical models have long suggested could efficiently produce high-energy neutrinos," Yuji Urata of MITOS Science Co., LTD. in Taiwan said in a statement. "If confirmed, Shadow Blaster would be the first-ever individual dusty star-forming galaxy directly linked to a high-energy neutrino event."

Thus far, no other credible candidates exist as potential sources for this high-energy neutrino, designated IC 210922A.

Chasing ghosts

Astronomers were alerted to the existence of IC 210922A half a decade ago when this high-energy neutrino event was detected by the IceCube Neutrino Observatory located in Antarctica. This set the astronomical community scouring space in the direction of the constellation Eridanus for potential sources for an electromagnetic counterpart to this event with a range of telescopes. This turned up no convincing gamma-ray, X-ray or optical counterpart for the neutrino detection, nor could any gamma-ray burst, supernova, or tidal disruption event (in which a black hole violently shreds a star) be linked with IC 210922A.

Urata and colleagues began their personal search with the James Clerk Maxwell Telescope (JCMT), operated by the East Asian Observatory, and the Submillimeter Array (SMA), discovering Shadow Blaster, a galaxy in the right position and with the right level of brightness to be associated with IC 210922A. The team followed this up with an investigation using the Atacama Large Millimeter/submillimeter Array (ALMA), a collection of 66 radio wave antennas in northern Chile.

The detection of this galaxy was possible because it is strongly gravitationally lensed. Gravitational lensing is a phenomenon that occurs when an object of great mass comes between Earth and a distant background source, curving the fabric of spacetime. As light from the background source navigates this curvature, its path is curved. This results in light from the lensed source arriving at different times to our telescopes, causing it to be amplified.

In the case of Shadow Blaster, before the team could learn anything about this distant galaxy, they had to discover more about the object serving as the intermediate gravitational lens, specifically what type of object it is, its mass, and its distance from us. To do this, they turned to the Gemini North telescope and its Gemini Multi-Object Spectrograph (GMOS) and the Gemini Near-InfraRed Spectrograph (GNIRS) instruments.

With the model of a gravitational lens determined, the team discovered that Shadow Blaster is a galaxy with an extremely compact heart filled with dense clouds of gas and dust that is fueling an intense burst of star formation. A region such as this has long been theorized to serve as a powerful particle accelerator. Because Shadow Blaster lacks a feeding supermassive black hole, this research shows that these regions can still serve as cosmic particle accelerators when they harbor sleeping black holes and in the absence of the powerful jets that erupt from active galactic nuclei (AGNs).

As for the overall population of neutrinos, this research could help account for that too. Intensely star-forming galaxies, or starburst galaxies, are believed to have been prevalent around 10 billion years ago in the early universe. Thus, these galaxies could have been producing a multitude of high-energy neutrinos. Proving that may prove difficult, however, as astronomers don't have the good fortune to find all of these galaxies lurking behind a gravitational lens, meaning they may be too faint and distant to study.

"Our analysis suggests that this population could contribute up to roughly 20% of the observed diffuse neutrino background measured by IceCube," Urata concluded,

The team's research was published on Wednesday (June 17) in the journal Nature Astronomy.

Celebrating its 340th birthday this year, the gravitational constant is the oldest fundamental constant in physics. "Big G" as it is affectionately known, was first placed at the heart of Newton's law of universal gravitation during its formulation in 1686 and formally published a year later as an estimate yet-to-be-measured in Newton's book Philosophiæ Naturalis Principia Mathematica. But after all these centuries, Big G is ironically still the fundamental constant with the least well-constrained value.

Scientists currently estimate a range of values arrived at for Big G, which means we can't be totally certain if we have a good understanding of gravity or if there is something missing from our formulation. That is a situation that Stephan Schlamminger of the National Institute of Standards and Technology (NIST) has spent the last ten years trying to resolve, an endeavor that ended with the opening of an envelope containing an unknown answer, a situation more usually associated with the Oscars or some other glitzy awards ceremony than a physics experiment.

In this case, however, the drama is warranted; Big G is so ubiquitous in the equations we use to describe the universe that the uncertainty in its value is somewhat uncomfortable for scientists, especially for metrologists (nothing to do with the weather, but scientists who study measurement) like Schlamminger.

"G is gravity's best-kept secret. It sits in this peculiar position: it is the oldest fundamental constant we know of, Newton wrote it down in 1687, and yet it remains the least precisely known of all of them," Schlamminger told Space.com. "That strikes me as one of the great unresolved embarrassments of physics."

Rethinking Big G

The gravitational constant was introduced as part of the equation that underpins Newton's law of universal gravitation, which describes the force of attraction acting between every particle in the universe, and which is inversely proportional to the square of the distance separating the centers of mass of those particles. While the masses and distances used in these equations are adjustable, the value of Big G remains fixed. Therefore, this fundamental constant is key to calculating the strength of gravity everywhere in the universe.

Of course, in 1915, Newton's theory of gravity was supplanted by Einstein's geometric theory of gravity, general relativity, which sees this fundamental force arise from the curvature of the fabric of spacetime (the four-dimensional unification of space and time) caused by objects with mass. However, Big G survived this paradigm shift, albeit with a slightly revised role.

"Big G is a fundamental constant. As such, it is baked into our universe and has a certain value that is the same for all time through all space," Schlamminger said. "It gives the strength of gravity in Newtonian physics. In Einstein's theory of gravity, it determines how elastic space-time is. The smaller G, the more resistant spacetime is to being warped or deformed by massive objects like stars or planets."

The first effort to measure Big G is credited to physicist Henry Cavendish in 1798. Cavendish was able to measure the gravitational attraction between large and small lead spheres, thereby calculating the density of Earth and arriving at the first accurate value for Big G.

However, even with the advances in scientific equipment and computing power made over the last 227 years, Big G has remained extremely difficult to measure.

"Gravity is by far the weakest of the four fundamental forces, which makes it extraordinarily difficult to isolate and measure precisely. You cannot shield against gravity the way you can shield against electric or magnetic fields," Schlamminger said. "Everything pulls on everything else, all the time."

Schlamminger explained that, unlike in the case of most physics experiments, in which scientists can, in his words, "crank up the signal," researchers are instead stuck working with whatever gravity delivers.

"We now have 17 measurements of G, and they still scatter more than they should. Nobody knows why," Schlamminger said. "We were just distraught by the large scatter in the data set. For a metrologist, it is unsatisfying having measurements that don't converge."

Opening the envelope

To perform their measurement of Big G, Schlamminger and a team of scientists replicated a precision experiment initially conducted by the International Bureau of Weights and Measures (BIPM) in Sèvres, France, transferring it to the NIST in Gaithersburg, Maryland, U.S. This came with its own risks, intellectual pitfalls that the researchers were careful to avoid.

"We wanted to make sure that we did not fall into the trap that's known as 'intellectual phase locking.' That happens when you look at your measurement result and compare it to the literature value or the previously measured value with the same instrument," Schlamminger said. "In this case, you may subconsciously stop when the measurement agrees with whatever expectation one has. This is not malice or intention. It happens at a subconscious level, and it is hard to guard against."

Schlamminger came up with a fascinating idea to avoid this: having a colleague set a value or "bias" to be added to the weights used in the experiment that the team would be unaware of. That meant Schlamminger and colleagues wouldn't know the value of Big G they had arrived at until the bias was revealed.

"We had the mass group add a bias to all the masses that they weighed for us. That bias was stored away in an envelope, and we only opened the envelope once we were happy with the self-consistency of our data," Schlamminger said.

This envelope was opened on July 11, 2024, two years after it was initially planned to be opened in 2022. This delay occurred because Schlamminger realized he had missed a subtle but important factor related to air pressure in his calculations.

The Big G value arrived by the team was 0.000064 lower than the value currently held by the Committee on Data of the International Science Council (CODATA).

"If you had a watch that is off by 0.000064 [seconds] after one year, your watch would be off by 34 minutes," Schlamminger explained.

This is a tiny difference, but it has interesting connotations. For instance, if the value of Big G arrived at by this team is correct, then Earth has a mass that is greater than the currently accepted value by 320,000,000,000,000,000,000 kilograms, or around 360 quadrillion tons.

"I want to be clear: the mystery is not solved. The underlying disagreement between experiments will still be there, waiting for someone to explain it," Schlamminger said. "That is what keeps this field alive."As for this metrologist, ten years of investigating Big G is sufficient for now.

"For now, I am stepping back from fundamental constants. These measurements take years, sometimes decades, and they take a lot out of you," Schlamminger concluded. "As for me, I am turning my attention to precision measurements of electrical quantities, resistors, and capacitors, where I hope to cause a similar amount of trouble!"

The team's results were published in the journal Metrologia.

Anyone who has been paying attention to cosmology over the past few years is aware of problems with our best attempts to explain why the universe is the way it is.

Our standard model, Lambda-CDM (or LCDM), is one of the most successful theories in the history of science. It accounts for the cosmic microwave background, the large-scale distribution of galaxies, the abundances of light elements, and basically every other large-scale observation we throw at it. The trouble lies with that capital L. Lambda is the cosmological constant, Einstein's placeholder for the energy of empty space, and it does the heavy lifting of explaining why the universe's expansion is accelerating.

The trouble is that we have no idea why Lambda has the value it does. Quantum field theory predicts a value roughly 122 orders of magnitude larger than what we measure  — one of the worst predictions in the history of physics. On top of that, the universe seems to be expanding at different rates depending on whether we measure it locally or infer it from the early-universe data, a stubborn disagreement known as the Hubble tension. Neither problem has gone away despite decades of work.

In a new paper posted to the arXiv preprint server, theoretical physicist Savvas Koushiappas of Brown University has put forward an unusual proposal. The universe, he argues, may have its own version of Heisenberg's uncertainty principle. Its size and its rate of expansion can't be simultaneously specified with perfect precision, and that fundamental fuzziness might be enough to explain dark energy without invoking any new physics at all.

Koushiappas's proposal sidesteps both. Instead of adding new particles or new fields, he asks what happens if we treat the universe's scale factor (essentially, its size) and its expansion rate as quantum mechanical operators that don't quite commute. In ordinary quantum mechanics, the same kind of non-commutation is what gives us the uncertainty principle: position and momentum can't both be pinned down at once. Apply the same idea to the universe as a whole and you get a deformed version of the Friedmann equation, the master equation that describes how the cosmos grows.

The deformation depends on a single free exponent. When that exponent is positive, the modified Friedmann equation naturally produces late-time accelerated expansion. No dark energy required. The universe behaves as if it had a built-in cosmological constant, but the acceleration comes from the geometry of its own quantum fuzziness rather than from some mysterious vacuum energy.

It gets more interesting. The same equation also predicts that the dark-energy-like behavior shouldn't be perfectly constant. The effective equation-of-state parameter (a number cosmologists use to characterize dark energy, which equals exactly -1 for a true cosmological constant) comes out slightly greater than -1 in this model. That is exactly the kind of deviation that current surveys like DESI have been hinting at, and which next-generation surveys should be able to confirm or rule out.

And if you flip the sign of the exponent, the same machinery does something else entirely. Instead of accelerating the late universe, it smooths out the early universe, replacing the Big Bang singularity with what Koushiappas calls a "classical bounce." The cosmos contracts to a minimum size, then expands. No infinite density, no breakdown of physics at t=0.

There are caveats. This is a single-author theoretical paper, not an observation, and the math is doing a lot of work. The model assumes a spatially flat universe, which is fine given current data. It also requires the expansion rate to be a well-behaved quantum operator, which in turn fixes one of the free parameters. The big question is whether the specific deviations from Lambda-CDM that this model predicts actually show up in the data, or whether the universe stubbornly insists on a value of -1 for the dark energy equation of state.

We should know soon. The Dark Energy Spectroscopic Instrument, the Euclid mission, and the Vera C. Rubin Observatory are all in the business of measuring exactly the quantities that this model predicts will deviate from a pure cosmological constant. If they keep finding hints of an equation of state slightly above -1, Koushiappas's cosmic uncertainty principle is going to start looking very interesting indeed.

Radioactive stardust remnants from stellar explosions have been found trapped in ice in Antarctica. These cosmic remains serve as clues that help uncover the history of our solar system, researchers have found in a new study.

Across the universe, we find colossal interstellar clouds of gas, dust, and plasma that lie between stars. Our own solar system is currently passing through such a cloud, known as the Local Interstellar Cloud, nicknamed the "Local Fluff." These clouds can accumulate matter as they float through the cosmos, and that matter can sometimes end up on Earth as our planet passes through the Local Fluff. In a new study of some of this matter, researchers have found a byproduct of ancient supernovas, a radioactive iron isotope known as iron-60 (60Fe), that got stuck in the cloud and ended up embedded in Antarctic ice.

"We found supernova-produced 60Fe in Antarctic ice," lead author Dominik Koll, from the Institute of Ion Beam Physics and Materials Research at HZDR, told Space.com. "If there is 60Fe condensed into dust particles (stardust) then this dust can penetrate the shielding of the solar system and end up on Earth."

So, how did researchers know that this iron isotope found in Antarctic ice was hitchhiking on an interstellar cloud from an ancient stellar explosion?

In 2019, Koll was part of a research team that detected 60Fe atoms in Antarctic snow. "We didn't know where it came from," he said. "So we continued working on it tracing the influx back … and we got the answer that it is related to the local interstellar cloud."

The team analyzed over 661 pounds (300 kilograms) of samples of ice from Antarctica dating back 40,000 to 80,000 years. This is the timeframe during which the team suspects the supernova took place, blasting the material into space only to be embedded in the cloud. After melting and chemically treating the ice and then using a technique known as accelerator mass spectrometry, which essentially speeds up ions, allowing researchers to separate isotopes from one another, they were able to look at and count individual atoms of this isotope in their samples.

"We looked for single atoms of the radioactive isotope 60Fe," Koll said. "This isotope is a fingerprint of exploding stars. Our hypothesis was that 60Fe might be within the local interstellar cloud if it originates from stellar explosions (that was postulated by modellers)."

The team compared the amount of the iron isotope that they found in recent snow to the amount in this newly-sampled ancient ice. And they found less 60Fe in the much older samples, suggesting that less iron-60 reached Earth between 40,000 and 80,000 years ago than in more recent times.

"This result suggests that less interstellar dust was reaching Earth during that period," Koll said. "This is a remarkable change on a comparatively short astrophysical timescale and does not fit the long timescales of the iron-60 deposits that landed here millions of years ago. Instead, we needed to look for a smaller, more local source for the isotope."

And this mystery source? These researchers think that it's most likely a stellar explosion that took place in the region of the Local Interstellar Cloud

"This means that the clouds surrounding the solar system are linked to a stellar explosion," Koll said in a statement. "And for the first time, this gives us the opportunity to investigate the origin of these clouds."

Our solar system has been traveling through the Local Interstellar Cloud for between 40,000 and 124,000 years, researchers have suggested, though it will only be another few thousand years until we are through.

This team aims to conduct more investigation to further confirm and expand their results by studying ice samples from even farther back in time, to a time before the solar system began traveling through this cloud.

This work was described in a study published May 13 in the journal Physical Review Letters.

On Earth, the Large Hadron Collider can smash atoms together and accelerate particles to near light speeds — but in space, there are high-energy cosmic rays with over 10 million times more power than even those zippy particles. And now, new research suggests such cosmic rays may hide a secret that is the key to unlocking a 60-year-old space puzzle.

One of these cosmic rays for instance, dubbed the Amaterasu particle (after the Japanese sun goddess) slammed into Earth in 2021 with an energy 40 million times greater than particles slammed together at the Large Hadron Collider (LHC). Amaterasu is considered the second most powerful cosmic ray ever detected — after the aptly named "Oh-My-God particle" detected back in 1991. However, the origins of these particles, and the sources that accelerated them to such high energies, are shrouded in mystery.

Traveling with the kinetic energy equivalent to that of a fast-moving tennis ball (a lot for a single cosmic-ray particle), the Amaterasu deepened that mystery as it appears to have originated from a void-like region with no obvious source. However, researchers finally think they may have hit upon an answer. A new study's team thinks the highest-energy cosmic rays may actually be atomic nuclei of elements heavier than iron. Could this be the missing link in our understanding of which mysterious violent events fling these intense particles toward Earth?

"The origins and acceleration mechanisms of ultrahigh-energy cosmic rays have been among the biggest mysteries in the field for more than 60 years, since the first example was reported," team leader Kohta Murase, of Penn State's Eberly College of Science, said in a statement. "Ultrahigh-energy cosmic rays can only be accelerated by some of the most powerful sources in the universe. When we detect individual cosmic-ray particles such as the Amaterasu particle here on Earth, we can often use their energies, arrival directions, and expected magnetic deflections to infer their possible cosmic sources."

Many sources have been proposed as the origins of high-energy cosmic rays, including the collapse of a massive star to form a neutron star or a black hole or the collision of two neutron stars themselves. For context, the matter that composes neutron stars is so dense that if a mere teaspoon of it were brought to Earth, it would weigh about 10 million tons, which is the same as 85,000 adult blue whales (try getting them on one teaspoon).

So, compressing a body with the mass of the sun to a width of around 12 miles (20 kilometers) is already incredibly violent — consider two of those compressed bodies meeting.

"These highest-energy cosmic rays are thought to come from extreme astrophysical sources, like two neutron stars colliding or a massive star collapsing," Murase said. "For many cosmic-ray events taken together, their energy distribution, arrival-direction pattern, and statistically inferred composition provide important clues about where these particles come from and how they are accelerated."

If Murase and fellow researchers are correct that cosmic rays may be the nuclei of elements heavier than iron, then this neutron star collision story may have some real footing at last.

To understand these high-energy particles and their origins, Murase and colleagues performed simulations tracking how cosmic rays of different masses would lose energy as they passed through vast cosmic distances to reach Earth. What this revealed was that atomic nuclei heavier than the atomic nucleus of iron lost energy much more slowly than lighter particles.

"Our research showed that at energies comparable to that of the Amaterasu particle, ultraheavy nuclei lose energy more slowly than protons or intermediate-mass nuclei, making them better able to survive cosmic distances and reach Earth at extreme energies," Murase said. "We are not saying that all ultrahigh-energy cosmic rays are ultraheavy nuclei. But if some of the highest-energy events are ultraheavy nuclei, that would impact how we search for their sources."

The team was also able to place constraints on how many heavy nuclei cosmic rays account for the overall population of high-energy cosmic rays.

"The most promising sites for producing and accelerating such ultraheavy nuclei are massive star deaths involving explosive collapse into black holes or strongly magnetized neutron stars, as well as binary neutron-star mergers known to be powerful gravitational-wave emitters," Murase said. "These violent cosmic phenomena can also power gamma-ray bursts that are among the most energetic explosions in the universe.

"A contribution from these sources could also help explain a possible difference seen between the northern and southern skies in the ultrahigh-energy cosmic-ray spectrum. If ultraheavy nuclei contribute significantly at the highest energies, future data should indicate a composition heavier than iron."

These results were published on Thursday (May 7) in the journal Physical Review Letters.

The Whirlpool Galaxy sprawls across the cosmos in this striking new snapshot from NASA's James Webb Space Telescope (JWST).

The galaxy, formally known as M51 (Messier 51), stretches out its spiral arms, glowing brightly in the darkness of space. While the galaxy's many limbs have been spotted before by the Hubble Space Telescope and even amateur astronomers, this image captures a uniquely striking view of its galactic beauty.

What is it?

The Whirlpool Galaxy was captured in this image by JWST's Near-Infrared Camera (NIRCam), according to a statement. This is JWST's primary instrument for seeing the universe in near-infrared light, which is a range of the electromagnetic wavelengths just out of our eyes' reach.

By seeing in near-infrared, NIRCam was able to capture this incredible view of part of the Whirlpool Galaxy. Located in the constellation Canes Vanatici, the spiral galaxy is made up of long swirls of gas and dust speckled with stars.

Beyond being just a beautiful cosmic sight, the formations of dust and gas that comprise this galaxy are actually a star-forming region. Here, gases like hydrogen and dust are compressed, condensing into new stars.

Why is it incredible?

This image shows only a section of the incredibly expansive spiral galaxy. The galaxy's red and orange spiral arms bending outward can measure tens or even hundreds of light-years across.

The full galaxy measures an incredible 76,900 light-years across. While this is an enormous size for any object or region, our own Milky Way galaxy measures over 100,000 light-years in diameter. But size and distances get fairly massive when we're talking on a cosmic scale. The Whirlpool Galaxy is a whopping 31 million light-years away from our own, but it's still considered one of our closer neighbors.

Something that has made the Whirlpool Galaxy beloved is its visibility. With an apparent magnitude of +8.4, skywatchers and amateur astronomers using small telescopes or even just binoculars are able to spot the galaxy and its spiral shape.

The world's first space-based neutrino detector launched to space last week to study elusive neutrino particles that constantly bombard Earth. The mission will test technology that could help researchers in the future to unravel hidden processes taking place deep inside the sun.

The detector, made of crystals of gallium and tungsten, is embedded in a 3U cubesat (about 12 inches long and 4 inches wide, an equivalent to 30 and 10 centimeters), which will orbit the planet at the altitude of 310 miles (500 kilometers) for about two years. The small instrument rode to orbit on the SpaceX CAS500-2 rideshare mission on May 3.

The project, called SNAPPY (for Solar Neutrino Astro-Particle PhYsic), was conceived by Wichita State University professor of physics and mathematics Nickolas Solomey. The project aims to validate the underlying technology for a future mission that could someday take a neutrino detector to the vicinity of the sun. "Neutrinos on Earth are pretty rare, so to detect neutrinos on Earth, you need very big detectors," Solomey told Space.com. "But closer to the sun, the number of neutrinos is a thousand and more times larger than here on Earth, which means that a one kilogram detector that we launch on a spacecraft and put closer to the sun is going to act like a thousand-kilogram detector here on Earth."

Neutrinos are near massless particles that emerge during natural nuclear decay, in nuclear fission reactions such as those taking place in nuclear reactors, and in nuclear fusion processes inside stars. Despite being the most abundant particles in the universe (tens of trillions of neutrinos pass through your body every second, according to the U.S. Department of Energy), neutrinos are notoriously difficult to detect.

Their elusive nature is caused by their barely there mass and lack of electric charge. To register the presence of neutrinos on Earth usually requires massive detectors buried deep underground. The neutrino's sparse reactions with matter are caused by the weak nuclear force, which guides the process of radioactive decay.

When a neutrino interacts with the nuclei of atoms, it transforms into an electron and a couple of more exotic particles known as muons and tau particles. To make sure the muons and electrons detected by the detectors really come from neutrino interactions, the detectors need to be placed deep underground where other cosmic particles cannot reach. The world's largest neutrino detector, China's Jiangmen Underground Neutrino Observatory, is buried 2,300 feet deep (700 meters) underground. The IceCube Neutrino Observatory on the South Pole sits even deeper — between 4,750 and 8,040 feet (1,450 and 2,450 meters) deep in the ice sheet.

The universe is awash with neutrinos that have been cruising through space since the Big Bang. But many also come from inside the sun. Yet, others reach our planet after being thrust into space in distant supernova explosions (the final blasts of stars that run out of fuel in their cores).

The high concentrations of neutrinos near the sun is what interests Solomey. The Snappy detector, currently undergoing testing in orbit, has a simple purpose — to validate that neutrino detection in space works. The gallium-based detector aboard the cubesat is also more sensitive to neutrino impacts than the argon-based detectors mostly used on Earth.

Solomey hopes that if the experiment proves successful, it might persuade NASA to place a neutrino detector on a possible future mission towards the sun.

"We could do a huge amount of solar neutrino interaction detections, but we could also increase the position resolution to get the image of the solar fusion shells that are around the core," Solomey explained. "We could study particle physics, the transport of the solar neutrinos as they get out of the sun and head towards deep space and some of them go towards Earth."

Because of the exceptional sensitivity of the gallium-based detector, Solomey thinks the team might be able to catch even the less energetic neutrinos that evade Earth-based detection.

Neutrinos come in different "flavors" based on the processes that created them. Solomey thinks that by analyzing en masse the neutrino flux streaming from the sun, researchers could open a unique window into the life-giving fusion processes that take place deep inside the star's core, far away from the reach of any human-made scientific instruments.

Because neutrinos barely interact with matter, they emerge from the immense depths of the sun within seconds of being born, said Solomey. On the other hand, scientists estimate that it takes some 100,000 years for the physical matter to bubble up the 435,000 miles (700,000 kilometers) from the sun's core to its surface.

"It's like putting a microscope into the core of the sun," said Solomey. "There are different types of fusion processes that occur in different layers away from the sun's core, and we could look at and study the structure of the solar fusion core looking at these different kinds of neutrinos."

Could Uranus and Neptune be full of rocks? One new study thinks so.

Uranus and Neptune are two planets that have historically been classified and thought of as "ice giants," orbiting far out in the freezing edges of our solar system. But it's possible that our understanding of these planets' makeup could be totally off, and their atmospheres could be full of rocks, researchers suggest in a new study.

"We found out that both Uranus and Neptune have their outer shells made mostly of rocks (and hydrogen and helium gas)," study author Yamila Miguel of the Netherlands Institute for Space Research told Space.com. This "goes against the common belief that they are ice-giant planets."

These two planets both have inner rocky cores surrounded by icy mantles enveloped by a thick atmosphere that has been thought to contain hydrogen, helium and methane gases as well as silicate clouds. In some high pressure areas, the gaseous atmosphere becomes fluid — but the results of this study suggest these atmospheres could also be littered with rocks.

This research team was inspired to take a closer look at Neptune and Uranus thanks to recent research which has suggested that objects in the trans-Neptunian region, an icy region beyond Neptune, are more rocky than icy. Previous studies have suggested objects like Pluto, comets, and Kuiper belt bodies indeed have rocky atmospheres, the new study's researchers explained. "We thought, if those objects are made mostly of rocks, maybe Uranus and Neptune [are] as well?" Miguel said.

To get to their conclusions, the researchers modeled the composition of both Uranus and Neptune, simulating the planets' envelopes (combined inner and outer atmosphere), mantles and cores. Based on conditions like temperature throughout each planet's atmospheric envelopes, the team found the conditions would cause silicate clouds in certain areas of these atmospheres to condense into rocky material.

So, while Uranus and Neptune are known as ice giants, orbiting far from our sun in the outer reaches of the solar system, they're rockier than you might expect an "ice" planet to be, at least according to this study.

While "they might have quite some ice in their interiors," Miguel said, "they are definitely not completely icy as we used to believe."

Miguel asserts that these new findings could even warrant a conversation about re-classifying these planets. "We should indeed change their classification so as not to be misleading," they suggest. "Rather than 'icy' or 'rocky,' we should simply call them minor giants or something like that."

To be clear, this new study isn't a definitive new classification of these planetary giants. However, it does raise interesting questions about their makeup: Could their atmospheres really be full of rocks? Are there other major aspects of their composition that we haven't yet uncovered? What other mysteries lie in the cold, far corners of our cosmic neighborhood?

This work was described in a study published May 5 in the journal Astronomy & Astrophysics.

When you think of air pollution from wildfires, you probably picture the thick plumes of smoke and ash that waft into the atmosphere during a blaze. And if you've lived in an area that’s been enveloped by these emissions, you know to stay inside or wear a mask when the light tints red and gets hazy.

But this thick cloud isn't the only component of wildfire smoke that carries a health risk. Now, new research based on satellite data helps quantify the impact of an "invisible" wildfire pollutant: ground-level ozone. It would appear the yearly human cost of this hidden consequence lies in the thousands.

Over the past few decades, climate change — primarily driven by human activities like burning coal — has turned wildfire smoke from an occasional, regional-specific concern to a major source of air pollution in the U.S. Since the 1990s, the area burned by wildfires in the country each year has roughly doubled. This means the amount of pollution released by these fires is on the rise, too.

Researchers have therefore been scrambling to quantify what risk all that smoke poses for human health. So far, however, most of these efforts have focused on fine particulate matter, or PM2.5. This is made up of tiny bits of ash, dust, carbon or other material less than 2.5 microns across that get released into the air from fires or other sources, like industrial emissions. Scientists know that high PM2.5 exposure is hazardous to human health — it can exacerbate conditions like heart disease and asthma, and even damage lung tissue directly.

But PM2.5 is not the only type of pollutant that fills the air during wildfires. The blazes generate a complex cocktail of compounds, including ground-level ozone, one of the main ingredients in smog. Like PM2.5, ozone can mess with people's lungs and cardiovascular systems. But the two pollutants have very different pathways to formation. While fine particulate matter is made of charred bits flung directly into the atmosphere by wildfires, ozone forms after the fact, when nitrogen oxides and volatile organic compounds interact with light.

"It's what we call a secondary pollutant," Minghao Qiu, an atmospheric scientist at Stony Brook University and co-author of the new study, told Space.com.

While the health impacts of PM2.5 from wildfire smoke are pretty well-documented, fire-generated ozone has been overlooked. That’s a problem, Qiu says, because "high ozone days don't necessarily coincide with high PM2.5 days."

To help determine the effects of smoke ozone on health, Qiu and his colleagues looked at nearly 20 years of satellite data, meteorological records and ozone measurements. Unlike fine particulate matter, ozone pollution is not visible to the naked eye, but scientists can detect it in the ultraviolet spectrum.

The researchers found that certain regions of the U.S. were more likely to accumulate ozone from wildfires than others; states like Texas, Louisiana, Arkansas, Mississippi and Florida were at particular risk. They also estimated that wildfire-derived ozone was responsible for 2,045 excess deaths, on average, per year across the U.S. — nearly 16% of all deaths attributed to wildfire smoke.

That number is also increasing. The estimated deaths from smoke ozone in 2006 alone was around 100; by 2023 it was close to 10,000.

This outcome appears to be undermining gains made from regulations around ozone emissions under the Clean Air Act. While overall ozone-related deaths in the U.S. have been trending downward for the last two decades, smoke ozone is starting to push those numbers back up.

This study is a good start for establishing risk analysis for ozone, says Qiu, but there's still a long way to go before researchers fully grasp the health impacts of wildfire smoke. For example, wildfires often release heavy metals like lead into the atmosphere, along with aromatic hydrocarbons and other pollutants. More research is needed to determine how these compounds affect mortality — and how they might compound with each other. "We don't fully understand the impacts on health when you are exposed to all those chemicals together," Qiu says. He and his colleagues are already working on follow-up studies.

But future work may be hamstrung by federal funding cuts. Much of the data used in the new study was originally collected by satellites and monitoring stations operated by NASA and the National Oceanic and Atmospheric Administration (NOAA). Under the current Trump administration, NASA faces a proposed 47% cut to its science budget in 2027. NOAA faces a 26% reduction, focused largely on eliminating climate monitoring programs. Without these crucial projects, it will be much harder to disentangle the health costs of wildfire pollution, let alone predict future fire risk.

The study was published on April 29 in the journal Science Advances.

Using NASA data and machine learning, scientists have found over 10,000 possible new planets in a single survey.

In a new study, researchers used machine learning to perform a sweeping survey of data from NASA's exoplanet-hunting Transiting Exoplanet Survey Satellite (TESS). As a result, they and uncovered exactly 10,091 candidate planets that had never been seen before. To clarify, when planets beyond our solar system (otherwise known as exoplanets) are first spotted, they are considered "candidates" until they can be confirmed as such with the right amount of evidence. Some of these candidates might not end up being planets after all — some could end up being other objects or even just "noise" in the data.

To date, humanity has discovered over 6,200 confirmed exoplanets, or planets outside of our solar system, according to NASA's Exoplanet Archive. But soon, thanks to all these new candidates, we could be adding a ton of worlds to the mix.

This major haul of exoplanet candidates, however, may beg the question: Why haven't these thousands of planets been seen before? In fact, TESS has been operational since 2018, and has been continuing on its extended mission since 2020.

Well, TESS operates by observing planets "transiting," or passing in front of, their stars. In other words, when an exoplanet is orbiting its star, at some point it will cross the face of the star from TESS' view. When this happens, the star appears to dim. TESS can measure that dimming, thereby revealing information about the planet passing in front of its star. Planets orbiting brighter stars are easier to spot because the transits are clearer.

However, this new study pulled data from fainter stars.

The survey actually looked at stars 16 times fainter than those typically targeted by TESS. Using machine learning, a type of artificial intelligence, the team surveyed over 83 million stars that were observed during TESS' first year of observations. Of these many millions of faint stars TESS looked at, 10,091 appeared to have transiting, planet-like objects never seen before.

Jackpot

Of course, some of the 10,091 planet candidates might turn out to not be planets, so this research team wanted to start further testing to confirm these results. And in doing so, they were able to confirm one of the candidates: a planet called TIC 183374187 b. This world appears to be a hot Jupiter, a gas giant that orbits very close to its host star — which is why it's so hot — and has a mass similar to Jupiter's.

But besides confirming all the exoplanets spotted with this research, the team also intends to take things a step further. While this study used the first year of TESS data, the research team aims to continue with a follow-up study using TESS' second year of data, lead author Joshua Roth, a graduate researcher at Princeton University, told IFLScience.

This boom in exoplanet discovery comes just about 30 years since the first exoplanet to be confirmed, 51 Pegasi b, was found in 1995. With that first confirmation, scientists were able to definitively say what they had thought likely true for years — that planets exist around other stars outside of our solar system. Since then, NASA missions like TESS and Kepler have provided data that has grown the field tremendously.

Looking to the future, in addition to incorporating techniques like machine learning as this team has done, NASA's upcoming Nancy Grace Roman Space Telescope will continue to expand exoplanet science with its Coronagraph Instrument which will make direct observations of worlds beyond our cosmic neighborhood. Rather than increase the number of exoplanets discovered, this instrument will allow for more in-depth study of these worlds and their atmospheres. As of writing this article, that telescope is slated to launch no earlier than early September 2026.

And even farther into the future, NASA aims to expand the field yet again with its Habitable Worlds Observatory, which is currently being built.

This work was published April 28 in The Astrophysical Journal.

Dark energy and dark matter remain some of the biggest mysteries in the universe. But with amazing new science and technologies, we're putting together pieces of this strange puzzle.

In a brilliant new 3D map, you can see a fantastic visual representation of the cosmos, which will allow scientists to investigate dark energy further.

Read more: A dark energy tool just created the most comprehensive 3D map of our universe ever: 'This is a major paradigm shift'

What is it?

Dark energy remains a complete unknown. In essence, it is the explanation for why our universe is expanding at an accelerated rate over time. But what this mysterious force (or not force) driving this acceleration is remains a mystery.

On April 14, the Dark Energy Spectroscopic Instrument (DESI) completed the largest 3D map of the universe ever in an effort to investigate dark energy.

Why is it incredible?

Our expanding universe holds countless unknowns. But to be able to see the universe visually, even three-dimensionally, is something truly spectacular.

In this image, every single point of light is a galaxy, with Earth at the center. It's a breathtaking view of our ever-expanding universe.

Space weather refers to the influence of solar activity on the Earth and the near-Earth environment. Solar flares, coronal mass ejections (CMEs) and solar energetic particles can disrupt satellite operations, damage power grids, and risk the health of aircrew and astronauts.

The impacts of space weather fall onto a spectrum. Lower impacts of space weather are experienced often, as satellite operators frequently adjust satellite orbits to deal with the loss in altitude resulting from solar flares. Larger impacts of space weather, however, are far rarer.

In January 2026, the U.K's Science and Technology Facilities Council (STFC) released the fourth edition of Summary of space weather worst-case environments, a report exploring what a "worst-case scenario" might look like. In this context, a worst-case event refers to something that occurs roughly once every 100 to 200 years, similar in scale to the Carrington Event.

The report focuses on how such an event could impact modern technology, something explored in a previous article. But it also highlights another important aspect: how extreme space weather events could influence human behavior.

Let's take a closer look.

Rampant conspiracy theories

If you've spent time on social media, you've likely encountered conspiracy theories, from moon landing denial to flat Earth claims. Space weather is no exception.

The report highlights that a lack of public understanding makes society particularly vulnerable to misinformation. A 2014 U.K. survey found that 46% of adults had never heard of space weather, while a further 29% had heard of the term but knew almost nothing about it.

With limited awareness, scientific communication risks being drowned out by misinformation spreading through what the report calls the "echo chamber effects of social media." Fear-driven and sensational narratives could take hold, increasing public anxiety and amplifying other behavioral risks.

the term, but knew almost nothing about it. (With some mainstream space weather events occurring since then, perhaps these statistics have since improved. But with a populous unknowledgeable on the subject, the document discusses that scientific communication and expert advice may be undermined by conspiracy theories traveling

Panic buying

We've seen how quickly public behavior can shift during crises. During the COVID-19 pandemic, panic buying led to widespread shortages of everyday items like toilet paper — in part creating the very problem people feared.

The report suggests similar behavior could occur during an extreme space weather event. As warnings of potential disruptions — such as power outages — spread, people may rush to stockpile essentials like food, fuel and water.

Even without direct damage to supply chains, the surge in demand alone could lead to shortages and long wait times, demonstrating how human behavior can worsen the overall impact of a crisis.

Rising public disorder

Public response to government action during emergencies is not always uniform.

While some people view measures as necessary and protective, others may see them as excessive or unfair. The report warns that similar tensions could emerge during a severe space weather event.

For example, in the event of widespread power outages, perceived inequalities in how power is restored, with some regions prioritized over other could trigger public frustration. In extreme cases, this could act as a "major catalyst for protests", particularly if communities feel they are being treated unfairly.

Religious and extreme belief responses

The report also explores a lesser-known concept: Millenarianism — the belief that a major event could trigger the end of the world or a profound societal transformation.

In the context of extreme space weather, some individuals or groups may interpret such an event as an impending apocalypse.

History provides sobering examples. In 1997, members of the Heaven's Gate cult died by suicide following the appearance of Comet Hale-Bopp. In 1994, members of the Order of the Solar Temple died in a series of tragic events in Switzerland.

While such cases are rare and difficult to predict, the reprot raises concerns that extreme space weather — particularly if widely misunderstood — could trigger similar reactions among vulnerable groups. In today's digital world, where ideas spread rapidly online, the boundary between fringe beliefs and large communities can become blurred.

A link between technology and behavior

A key takeaway from the summary of space weather worst-case environments is that the impacts of extreme space weather cannot be separated into purely technological or purely human effects — the two are closely linked.

Disruptions to infrastructure can influence behavior, while human reactions can, in turn, amplify the overall impact of an event.

Improving resilience means addressing both sides of the equation. Strengthening infrastructure is essential, but so is improving public understanding of space weather and how it affects our lives.

In a world increasingly shaped by both technology and information, even small steps — like sharing accurate knowledge — can help reduce the risks. If you are reading this, perhaps you could contribute to the cause by telling a friend or family member about space weather!

For many of us, checking the weather is part of daily life. But, in an increasingly technology-dependent world, there is another kind of forecast we can't afford to ignore: space weather.

Space weather refers to activity on the sun and how it affects Earth and the space around it, a complex, chaotic system scientists are working to understand, forecast and mitigate.

There are three primary types of space weather (radio blackouts, geomagnetic storms and solar radiation storms), each relating to different processes on the sun. Solar flares, intense bursts of energy in the sun's atmosphere, can trigger radio blackouts on Earth by increasing ionization in the upper atmosphere, which disrupts radio signals. Geomagnetic storms, on the other hand, are caused by the impact of rapid streams of plasma on Earth's magnetic field, most dramatic during violent eruptions of plasma (coronal mass ejections) from the sun. Finally, solar radiation storms are caused by the arrival of high- energy protons and electrons coming from the sun.

We have experienced several strong space weather events over the past few years, with the strongest in May 2024. During this period, a loss of satellite navigation resulted in a $500 million loss to the U.S. agricultural industry. This was the strongest space weather event since October 2003, when Sweden and South Africa experienced widespread power outages. But what would a worst-case scenario look like?

In January 2026, a technical report from the U.K.'s Science and Technology Facilities Council (STFC) set out to answer this question in the fourth edition of: Summary of space weather worst-case environments. The document covers all terrestrial impacts of space weather (not including outer space operations), spanning 80 pages.

But what do we mean by 'worst-case scenario'? In reality, it is not worthwhile planning for events that might happen once every million years. Instead, scientists and policy makers consider a 'worst-case' space weather event to be the type of event we might experience every 100-200 years. The report outlines how a worst-case space weather event over this timescale could affect everything from power grids to satellites. Although the scenarios are based on conditions in the U.K., similar impacts could be felt in other parts of the world — especially at similar latitudes.

Could space weather knock out power?

During geomagnetic storms, additional electric currents are created in power lines on the ground. If the additional electric currents, plus those already flowing through the system, are strong enough, then they can trip power grid safety systems and potentially lead to regional power outages. The report also explains how this process can cause direct damage and premature aging of transformers, lowering the grid capacity in the months (or even years) after the space weather event.

Satellites at risk

According to the report, one of the most immediate impacts of a severe space weather event would be felt in orbit. Satellites, which underpin everything from GPS to weather forecasting, are particularly vulnerable to both radiation and changes in Earth's atmosphere.

During an extreme space weather event, bursts of charged particles can damage onboard electronics and gradually degrade solar panels, shortening a spacecraft's lifespan by years. In the most severe cases, some satellite systems could fail permanently.

The report also highlights another disruptive effect of solar flares, whereby Earth's atmosphere can temporarily expand when heated by incoming X-rays from the sun. That increase in atmospheric drag can slow satellites down, causing them to lose altitude and potentially burn up above us.

We've already seen a version of this in recent years. Following heightened solar activity in 2022, up to 40 Starlink satellites re-entered Earth's atmosphere after launching during a solar flare. A worst-case scenario would amplify this effect, making it harder for operators to track spacecraft and space debris.

When signals fail

As you read this, radio signals are traveling through and around you. Our society relies on these signals, used in satellite navigation, mobile phone networks, WiFi, communication with flights and ships, and so on. Many of these systems will be disrupted during the worst-case space weather events.

Solar flares themselves produce radio waves, which can 'drown out' radio signals used on the ground. Systems reliant on detecting weak radio signals will be particularly at risk, including radar and global navigation systems. This will be a short-term effect, lasting around an hour on the daylit side of the Earth.

Many radio signals travel long distances by bouncing off a region of the upper atmosphere called the ionosphere. During geomagnetic storms, this layer becomes unstable, disrupting those signals. This can lead to widespread degradation and potential loss of satellite-based navigation and communications for several days. Many systems rely on satellite navigation in surprising ways, such as the US agricultural industry, which was impacted hard during the May 2024 extreme geomagnetic storm.

Radio communication in "Ultra-High Frequency" (UHF) and "Very-High Frequency" (VHF) ranges will also be disrupted for several days. These frequencies will not disrupt your mobile phone, but will interfere with the long-range communication systems used for planes and ships, likely leading to the grounding of flights. This grounding of flights is not necessarily a bad thing, as the report also discusses the risk of hazardous radiation exposure to aircrew, with a higher risk at higher latitudes. Aircrew may need to limit future radiation doses by limiting future flight duties, with pregnant crew particularly vulnerable.

While extreme space weather is unlikely to trigger a doomsday scenario, it could still have serious consequences for modern infrastructure.

The good news? Our ability to monitor the sun and forecast solar storms is improving, giving us more time to prepare for the next big event.

Editor's note: This article was updated on April 15 at 3:00 a.m. EDT to correct a typo it was a $500 million loss to agriculture, not $500 billion.

The world's most powerful particle accelerator, the Large Hadron Collider, has given scientists their best look yet at quark-gluon plasma, the primordial matter that filled the universe moments after the Big Bang.

During the first fractions of a second of the universe's existence, the cosmos was filled with a hot and dense primordial soup called quark-gluon plasma. At the nearly 17-mile-long circular particle accelerator, the Large Hadron Collider (LHC) that sits deep below the French Alps, CERN scientists recreated the quark-gluon plasma by smashing together atomic nuclei of iron at near-light speed. The project is called ALICE (A Large Ion Collider Experiment).

The ALICE team obtained new information about the quark-gluon plasma (and thus the conditions in the early universe) when they spotted a pattern common to collisions between protons — the particles found at the heart of atoms — collisions between protons and lead nuclei, and collisions between lead nuclei themselves. This pattern could reveal how the quark-gluon plasma formed right after the Big Bang, indicating it could be forged by smaller particle collisions than previously thought.

When scientists first started smashing protons together at the LHC, it was theorized that collisions between protons as well as between protons and lead would be too small to generate quark-gluon plasma. However, tantalizing signs of this primordial matter have recently been seen in these small collisions as well as in the collisions between lead nuclei.

One of the signatures of quark-gluon plasma and its formation is the fact that particles aren't emitted evenly, but in a preferred direction, which scientists call anisotropic flow. At intermediate speeds, the anisotropic flow of particles depends on the number of quarks that compose them. Baryons, particles composed of three quarks, exhibit a stronger flow than mesons, which are particles composed of two quarks.

Scientists theorize that this is linked to the process that brings quarks together to form larger particles. Baryons have more quarks and thus gain greater flow.

In new research the ALICE Collaboration explained how they measured the anisotropic flow for different mesons and baryons created by proton-proton and proton-lead collisions. By isolating particles flowing together, the team confirmed that, just as is seen in heavy collisions, these lighter collisions give rise to baryons with stronger flow and mesons with weaker flow at intermediate speeds.

"This is the first time we have observed, for a large interval in momentum and for multiple species, this flow pattern in a subset of proton collisions in which an unusually large number of particles are produced," David Dobrigkeit Chinellato, Physics Coordinator of the ALICE experiment, said in a statement. "Our results support the hypothesis that an expanding system of quarks is present even when the size of the collision system is small."

The ALICE team compared the flow observations they made to models of quark-gluon plasma formation, finding the flow pattern closely fit models that account for the formation of baryons and mesons. Models that don't factor in this quark coalescence, however, failed to replicate the observed flow pattern.

The researchers also found that even the best-fit models couldn't completely account for the observed flow. There are still some lingering discrepancies, wrinkles that the team thinks other collisions between particles with sizes between protons and iron could help to iron out.

"We expect that, with the oxygen collisions that were recorded in 2025, which bridge the gap between proton collisions and lead collisions, we will gain new insights into the nature and evolution of the quark-gluon plasma across different collision systems," ALICE Spokesperson Kai Schweda said in the statement.

Then, scientists will edge even closer to understanding the conditions found at the very dawn of the universe.

A paper about this research was published on March 20 in the journal Nature Communications.

A sweeping new satellite analysis shows that Antarctica has lost nearly 5,000 square miles (12,950 square kilometers) of grounded ice over the past three decades — an area roughly twice as big as Delaware — as warming ocean waters erode the continent's most vulnerable edges.

Led by scientists at the University of California, Irvine, the study traces how Antarctica's "grounding line" — the boundary where ice anchored to bedrock begins to float on the ocean — shifted between 1992 and 2025. Because that boundary marks where land-based ice begins contributing directly to sea level rise, its retreat signals ice-sheet instability and future ice mass loss.

"We've known it's critically important for 30 years, but this is the first time we've mapped it comprehensively across all of Antarctica over such a long time span," study lead author Eric Rignot of UC Irvine said in a statement.

Rignot and his colleagues analyzed data from a wide range of satellite missions operated by European, Canadian, Japanese, Italian, German and Argentine space agencies. Using radar instruments, the researchers tracked the vertical movements of floating ice shelves caused by ocean tides. Grounded ice remained fixed on bedrock, allowing them to pinpoint shifts in the grounding line over three decades with unprecedented precision.

The results show that about 77% of Antarctica's coastline experienced no detectable grounding-line migration since 1996, suggesting broad stability across much of the continent. But in vulnerable regions, particularly parts of West Antarctica, the Antarctic Peninsula and sections of East Antarctica, the study found "significant retreat."

The largest changes were detected along the Amundsen Sea coast of West Antarctica and in the Getz sector, where the grounding line in some places pulled back by as much as 26 miles (42 km) during the study period.

Retreat was most pronounced where deep underwater pathways funnel warm ocean water toward the base of glaciers, Rignot said. That warmer water melts ice from below, thinning floating shelves and weakening their ability to buttress the glaciers behind them.

"It's like the balloon that's not punctured everywhere, but where it is punctured, it's punctured deep," said Rignot.

The study also highlights a puzzling pattern along the northeast Antarctic Peninsula. In that area, several ice shelves collapsed before the study period and multiple glaciers have since retreated significantly, but researchers lack clear evidence that warm ocean water is driving the change.

"Something else is acting — it's still a question mark," Rignot said in the statement.

Beyond documenting what has already happened, the researchers say the new record provides a crucial real-world test for computer models used to project future sea level rise.

"Models have to demonstrate they can match this 30-year record to claim credibility for their projections," Rignot said in the statement. "That's the real value of this observational record: knowing that this grounding line migration has happened."

While much of Antarctica remains stable, Rignot cautioned that the current balance may not hold indefinitely.

"The flip side is that we should perhaps feel fortunate that all of Antarctica isn't reacting right now, because we would be in far more trouble," he said. "But that could be the next step."

This research is described in a paper published March 2 in the journal Proceedings of the National Academy of Sciences.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Time feels like the most basic feature of reality. Seconds tick, days pass and everything from planetary motion to human memory seems to unfold along a single, irreversible direction. We are born and we die, in exactly that order. We plan our lives around time, measure it obsessively and experience it as an unbroken flow from past to future. It feels so obvious that time moves forward that questioning it can seem almost pointless.

And yet, for more than a century, physics has struggled to say what time actually is. This struggle is not philosophical nitpicking. It sits at the heart of some of the deepest problems in science.

Modern physics relies on different, but equally important, frameworks. One is Albert Einstein's theory of general relativity, which describes the gravity and motion of large objects such as planets. Another is quantum mechanics, which rules the microcosmos of atoms and particles. And on an even larger scale, the standard model of cosmology describes the birth and evolution of the universe as a whole. All rely on time, yet they treat it in incompatible ways.

When physicists try to combine these theories into a single framework, time often behaves in unexpected and troubling ways. Sometimes it stretches. Sometimes it slows. Sometimes it disappears entirely.

Einstein's theory of relativity was, in fact, the first major blow to our everyday intuition about time. Time, Einstein showed, is not universal. It runs at different speeds depending on gravity and motion. Two observers moving relative to one another will disagree about which events happened at the same time. Time became something elastic, woven together with space into a four-dimensional fabric called spacetime.

Quantum mechanics made things even stranger. In quantum theory, time is not something the theory explains. It is simply assumed. The equations of quantum mechanics describe how systems evolve with respect to time, but time itself remains an external parameter, a background clock that sits outside the theory.

This mismatch becomes acute when physicists try to describe gravity at the quantum level, which is crucial for developing the much coveted theory of everything – which links the main fundamental theories. But in many attempts to create such a theory, time vanishes as a parameter from the fundamental equations altogether. The universe appears frozen, described by equations that make no reference to change.

This puzzle is known as the problem of time, and it remains one of the most persistent obstacles to a unified theory of physics. Despite enormous progress in cosmology and particle physics, we still lack a clear explanation for why time flows at all.

Now a relatively new approach to physics, building on a mathematical framework called information theory, developed by Claude Shannon in the 1940s, has started coming up with surprising answers.

Entropy and the arrow of time

When physicists try to explain the direction of time, they often turn to a concept called entropy. The second law of thermodynamics states that disorder tends to increase. A glass can fall and shatter into a mess, but the shards never spontaneously leap back together. This asymmetry between past and future is often identified with the arrow of time.

This idea has been enormously influential. It explains why many processes are irreversible, including why we remember the past but not the future. If the universe started in a state of low entropy, and is getting messier as it evolves, that appears to explain why time moves forward. But entropy does not fully solve the problem of time.

For one thing, the fundamental quantum mechanical equations of physics do not distinguish between past and future. The arrow of time emerges only when we consider large numbers of particles and statistical behaviour. This also raises a deeper question: why did the universe start in such a low-entropy state to begin with? Statistically, there are more ways for a universe to have high entropy than low entropy, just as there are more ways for a room to be messy than tidy. So why would it start in a state that is so improbable?

The information revolution

Over the past few decades, a quiet but far-reaching revolution has taken place in physics. Information, once treated as an abstract bookkeeping tool used to track states or probabilities, has increasingly been recognised as a physical quantity in its own right, just like matter or radiation. While entropy measures how many microscopic states are possible, information measures how physical interactions limit and record those possibilities.

This shift did not happen overnight. It emerged gradually, driven by puzzles at the intersection of thermodynamics, quantum mechanics and gravity, where treating information as merely mathematical began to produce contradictions.

One of the earliest cracks appeared in black hole physics. When Stephen Hawking showed that black holes emit thermal radiation, it raised a disturbing possibility: information about whatever falls into a black hole might be permanently lost as heat. That conclusion conflicted with quantum mechanics, which demands that the entirety of information be preserved.

Resolving this tension forced physicists to confront a deeper truth. Information is not optional. If we want a full description of the universe that includes quantum mechanics, information cannot simply disappear without undermining the foundations of physics. This realisation had profound consequences. It became clear that information has thermodynamic cost, that erasing it dissipates energy, and that storing it requires physical resources.

In parallel, surprising connections emerged between gravity and thermodynamics. It was shown that Einstein's equations can be derived from thermodynamic principles that link spacetime geometry directly to entropy and information. In this view, gravity doesn't behave exactly like a fundamental force.

Instead, gravity appears to be what physicists call "emergen" – a phenomenon describing something that's greater than the sum of its parts, arising from more fundamental constituents. Take temperature. We can all feel it, but on a fundamental level, a single particle can't have temperature. It's not a fundamental feature. Instead it only emerges as a result of many molecules moving collectively.

Similarly, gravity can be described as an emergent phenomenon, arising from statistical processes. Some physicists have even suggested that gravity itself may emerge from information, reflecting how information is distributed, encoded and processed.

These ideas invite a radical shift in perspective. Instead of treating spacetime as primary, and information as something that lives inside it, information may be the more fundamental ingredient from which spacetime itself emerges. Building on this research, my colleagues and I have explored a framework in which spacetime itself acts as a storage medium for information – and it has important consequences for how we view time.

In this approach, spacetime is not perfectly smooth, as relativity suggests, but composed of discrete elements, each with a finite capacity to record quantum information from passing particles and fields. These elements are not bits in the digital sense, but physical carriers of quantum information, capable of retaining memory of past interactions.

A useful way to picture them is to think of spacetime like a material made of tiny, memory-bearing cells. Just as a crystal lattice can store defects that appeared earlier in time, these microscopic spacetime elements can retain traces of the interactions that have passed through them. They are not particles in the usual sense described by the standard model of particle physics, but a more fundamental layer of physical structure that particle physics operates on rather than explains.

This has an important implication. If spacetime records information, then its present state reflects not only what exists now, but everything that has happened before. Regions that have experienced more interactions carry a different imprint of information than regions that have experienced fewer. The universe, in this view, does not merely evolve according to timeless laws applied to changing states. It remembers.

A recording cosmos

This memory is not metaphorical. Every physical interaction leaves an informational trace. Although the basic equations of quantum mechanics can be run forwards or backwards in time, real interactions never happen in isolation. They inevitably involve surroundings, leak information outward and leave lasting records of what has occurred. Once this information has spread into the wider environment, recovering it would require undoing not just a single event, but every physical change it caused along the way. In practice, that is impossible.

This is why information cannot be erased and broken cups do not reassemble. But the implication runs deeper. Each interaction writes something permanent into the structure of the universe, whether at the scale of atoms colliding or galaxies forming.

Geometry and information turn out to be deeply connected in this view. In our work, we have showed that how spacetime curves depends not only on mass and energy, as Einstein taught us, but also on how quantum information, particularly entanglement, is distributed. Entanglement is a quantum process that mysteriously links particles in distant regions of space – it enables them to share information despite the distance. And these informational links contribute to the effective geometry experienced by matter and radiation.

From this perspective, spacetime geometry is not just a response to what exists at a given moment, but to what has happened. Regions that have recorded many interactions tend, on average, to behave as if they curve more strongly, have stronger gravity, than regions that have recorded fewer.

This reframing subtly changes the role of spacetime. Instead of being a neutral arena in which events unfold, spacetime becomes an active participant. It stores information, constrains future dynamics and shapes how new interactions can occur. This naturally raises a deeper question. If spacetime records information, could time emerge from this recording process rather than being assumed from the start?

Time arising from information

Recently, we extended this informational perspective to time itself. Rather than treating time as a fundamental background parameter, we showed that temporal order emerges from irreversible information imprinting. In this view, time is not something added to physics by hand. It arises because information is written in physical processes and, under the known laws of thermodynamics and quantum physics, cannot be globally unwritten again. The idea is simple but far-reaching.

Every interaction, such as two particles crashing, writes information into the universe. These imprints accumulate. Because they cannot be erased, they define a natural ordering of events. Earlier states are those with fewer informational records. Later states are those with more.

Quantum equations do not prefer a direction of time, but the process of information spreading does. Once information has been spread out, there is no physical path back to a state in which it was localised. Temporal order is therefore anchored in this irreversibility, not in the equations themselves.

Time, in this view, is not something that exists independently of physical processes. It is the cumulative record of what has happened. Each interaction adds a new entry, and the arrow of time reflects the fact that this record only grows.

The future differs from the past because the universe contains more information about the past than it ever can about the future. This explains why time has a direction without relying on special, low-entropy initial conditions or purely statistical arguments. As long as interactions occur and information is irreversibly recorded, time advances.

Interestingly, this accumulated imprint of information may have observable consequences. At galactic scales, the residual information imprint behaves like an additional gravitational component, shaping how galaxies rotate without invoking new particles. Indeed, the unknown substance called dark matter was introduced to explain why galaxies and galaxy clusters rotate faster than their visible mass alone would allow.

In the informational picture, this extra gravitational pull does not come from invisible dark matter, but from the fact that spacetime itself has recorded a long history of interactions. Regions that have accumulated more informational imprints respond more strongly to motion and curvature, effectively boosting their gravity. Stars orbit faster not because more mass is present, but because the spacetime they move through carries a heavier informational memory of past interactions.

From this viewpoint, dark matter, dark energy and the arrow of time may all arise from a single underlying process: the irreversible accumulation of information.

Testing time

But could we ever test this theory? Ideas about time are often accused of being philosophical rather than scientific. Because time is so deeply woven into how we describe change, it is easy to assume that any attempt to rethink it must remain abstract. An informational approach, however, makes concrete predictions and connects directly to systems we can observe, model and in some cases experimentally probe.

Black holes provide a natural testing ground, as they seems to suggest information is erased. In the informational framework, this conflict is resolved by recognising that information is not destroyed but imprinted into spacetime before crossing the horizon. The black hole records it.

This has an important implication for time. As matter falls toward a black hole, interactions intensify and information imprinting accelerates. Time continues to advance locally because information continues to be written, even as classical notions of space and time break down near the horizon and appear to slow or freeze for distant observers.

As the black hole evaporates through Hawking radiation, the accumulated informational record does not vanish. Instead, it affects how radiation is emitted. The radiation should carry subtle signs that reflect the black hole's history. In other words, the outgoing radiation is not perfectly random. Its structure is shaped by the information previously recorded in spacetime. Detecting such signs remains beyond current technology, but they provide a clear target for future theoretical and observational work.

The same principles can be explored in much smaller, controlled systems. In laboratory experiments with quantum computers, qubits (the quantum computer equivalent of bits) can be treated as finite-capacity information cells, just like the spacetime ones. Researchers have shown that even when the underlying quantum equations are reversible, the way information is written, spread and retrieved can generate an effective arrow of time in the lab. These experiments allow physicists to test how information storage limits affect reversibility, without needing cosmological or astrophysical systems.

Extensions of the same framework suggest that informational imprinting is not limited to gravity. It may play a role across all fundamental forces of nature, including electromagnetism and the nuclear forces. If this is correct, then time's arrow should ultimately be traceable to how all interactions record information, not just gravitational ones. Testing this would involve looking for limits on reversibility or information recovery across different physical processes.

Taken together, these examples show that informational time is not an abstract reinterpretation. It links black holes, quantum experiments and fundamental interactions through a shared physical mechanism, one that can be explored, constrained and potentially falsified as our experimental reach continues to grow.

What time really is

Ideas about information do not replace relativity or quantum mechanics. In everyday conditions, informational time closely tracks the time measured by clocks. For most practical purposes, the familiar picture of time works extremely well. The difference appears in regimes where conventional descriptions struggle.

Near black hole horizons or during the earliest moments of the universe, the usual notion of time as a smooth, external coordinate becomes ambiguous. Informational time, by contrast, remains well defined as long as interactions occur and information is irreversibly recorded.

All this may leave you wondering what time really is. This shift reframes the longstanding debate. The question is no longer whether time must be assumed as a fundamental ingredient of the universe, but whether it reflects a deeper underlying process.

In this view, the arrow of time can emerge naturally from physical interactions that record information and cannot be undone. Time, then, is not a mysterious background parameter standing apart from physics. It is something the universe generates internally through its own dynamics. It is not ultimately a fundamental part of reality, but emerges from more basic constituents such as information.

Whether this framework turns out to be a final answer or a stepping stone remains to be seen. Like many ideas in fundamental physics, it will stand or fall based on how well it connects theory to observation. But it already suggests a striking change in perspective.

The universe does not simply exist in time. Time is something the universe continuously writes into itself.

Scientists are investigating the origin of one of the most energetic particles ever seen hitting Earth from space. The Amaterasu particle, named for the Japanese sun goddess, was first detected in 2021, carrying 40 million times more energy than particles accelerated by the world's largest and most powerful particle accelerator, the Large Hadron Collider (LHC).

Amaterasu is an example of a cosmic ray, energetic charged particles that race through space at nearly the speed of light. It is the second most energetic cosmic ray ever detected after the "Oh-My-God" particle, detected in 1991. Such high-energy particles are extremely rare, which means scientists would very much like to understand their origins — currently thought to involve the wreckage of supernova explosions and central regions of galaxies dominated by feeding supermassive black holes.

Deepening the puzzle of Amaterasu is the fact that it seems to have emerged from the "Local Void," a region of space devoid of galaxies and the extreme environments and violent conditions thought be the factories that launch high-energy cosmic rays.

Enter Francesca Capel and Nadine Bourriche, researchers at the Max Planck Institute for Physics, who have found that Amaterasu's origins may not be locked within the local void. Instead, this highly energetic particle may have emerged from a range of relatively local cosmic environments.

"Our results suggest that, rather than originating in a low-density region of space like the Local Void, the Amaterasu particle is more likely to have been produced in a nearby star-forming galaxy such as M82," Bourriche said in a statement.

The duo's findings emerged from a novel data-driven approach that allowed them to trace the possible path of Amaterasu through the cosmos. The team considered the journey of this high-energy cosmic ray through space under the influence of magnetic fields using a statistical technique called in three dimensions called Approximate Bayesian Computation.

"This approach works by comparing the results of realistic, physics-based simulations with actual observational data to infer the most probable source locations," Bourriche said.

The result of this analysis was a collection of "probability maps" all tracking back to possible Amaterasu origin points beyond the Local Void. The research has implications beyond the origins of this extraordinary goddess particle, however. The team's findings could help better pin down which powerful and violent cosmic events serve as high-energy cosmic ray factories.

"Exploring ultra-high-energy cosmic rays helps us to better understand how the Universe can accelerate matter to such energies, and also to identify environments where we can study the behavior of matter in such extreme conditions," Capel said. "Our goal is to develop advanced statistical analysis methods to exploit the available data to its full potential and gain a deeper understanding of the possible sources of these energetic particles."

The team's results were published on Jan. 28 in The Astrophysical Journal.

The National Oceanic and Atmospheric Administration (NOAA) has released an entrancing orbital view of "cloud streets" streaming away from the south Florida coast on Feb. 1, as freezing air surged southwards into the Gulf of Mexico and the Atlantic ocean.

What am I seeing?

Cloud streets have been known to form when cold air passes over warmer water, absorbing moisture from the waves below to create parallel belts of low-level clouds, which often align with the prevailing wind, according to NOAA.

The mesmerizing cloud formations occurred as Floridians endured some of the coldest temperatures of recent years, with the city of Tampa on the western coast of the peninsula reporting a freezing 30 degrees Fahrenheit (-1 degrees Celsius).

An orbital timelapse of the cloud streets (above) gives the impression of water churning in the wake of a speeding boat. A clear stretch of water can also be seen following the line of the coast, indicating regions of dry air that had yet to absorb enough moisture to manifest the spectacular clouds.

What captured the picture?

The cloud streets were captured by the Advanced Baseline Imager instrument mounted on NOAA's GOES-19 weather satellite, as it orbited 22,236 miles (35,785 kilometers) above Earth's equator.

GOES-19 launched on June 25, 2024 atop a SpaceX Falcon Heavy rocket from NASA's Kennedy Space Center in Florida before establishing itself in a geostationary orbit, where it travels at a height and velocity that perfectly matches Earth's rate of rotation. As a result, it always has the same view of Earth, which encompasses the Americas and Canada, along with a host of other nations.

The satellite is equipped with instruments that allow it to track terrestrial weather and potential environmental hazards, including the oceanic conditions that give rise to powerful hurricanes. GOES-19 is also armed with tools geared towards monitoring the sun and the space weather environment, which can impact life on Earth and the health of orbiting spacecraft.

Check out our explainer article on the different kinds of clouds and how they form to find out more!

Using the world's most powerful particle accelerator, CERN's Large Hadron Collider, scientists have discovered that the trillion-degree hot primordial "soup" that filled the cosmos for mere millionths of a second after the Big Bang actually behaved like a liquid, making it akin to a literal soup.

This primordial soup was composed of a plasma of particles called quarks and gluons that rapidly cooled, causing these two types of particles to fuse and create fundamental particles like protons and neutrons, which today sit at the heart of all atoms that make up the matter all around us. Today, quarks and gluons are only found locked up in the particles they comprise, with one exception. By smashing together heavy atoms of lead traveling at near-light speeds using the Large Hadron Collider (LHC), scientists can create a high-energy environment that briefly frees gluons and quarks from this atomic bondage, recreating the quark-gluon plasma of the early universe.

Using the 17-mile (27 kilometers) long accelerator located near Geneva, Switzerland, a team of researchers from the Massachusetts Institute of Technology (MIT) generated quark-gluon plasma. Within this pseudo-primordial soup, they observed quarks creating "wakes" as they raced through the plasma, akin to the trail created by a boat as it travels through water. This is the first evidence that this quark-gluon plasma reacts to particles speeding through it in the same way that liquid does, splashing and rippling, acting as a single unified liquid rather than randomly scattering as individual particles would. This cohesion means the plasma-quark gluon wasn't just a fluid, a term which can include a liquid or a gas, but acted as a liquid. Scientists say it could settle some long-standing questions about what the universe's earliest 'stuff' was like.

"It has been a long debate in our field on whether the plasma should respond to a quark," team member Yen-Jie Lee, professor of physics at MIT, said in a statement. "Now we see the plasma is incredibly dense, such that it is able to slow down a quark, and produces splashes and swirls like a liquid. "So quark-gluon plasma really is a primordial soup."

To observe the wakes created in quark-gluon plasma by travelling particles, Lee and colleagues used the LHC's Compact Muon Solenoid (CMS) detector to develop a technique that also allowed them to measure the size, speed, and extent of these wakes, and how long it takes for them to ebb and dissipate. This information could be critical to better understanding both the properties of quark-gluon plasma and how it behaved during the first microseconds of the cosmos.

"Studying how quark wakes bounce back and forth will give us new insights on the quark-gluon plasma's properties," Lee said. "With this experiment, we are taking a snapshot of this primordial quark soup."

You might want to blow on this soup for a while

The quark-gluon plasma wasn't just the first liquid to have existed in the universe, but with a temperature of many trillions of degrees, it is also the hottest liquid that ever existed. The primordial soup is considered to have been a near-perfect liquid, which means its quark and gluon contents flowed together as a smooth, frictionless fluid.

Though there are many models of quark-gluon plasma, one theory, dubbed the "hybrid model," suggests that this primordial soup should react like any other liquid when particles pass through it at speed. In the hybrid model, a jet of quarks moving through the quark-gluon plasma should create a wake as it causes this plasma ocean to ripple and splash.

There have been many experiments at the LHC and other particle accelerators that have attempted to see this effect in action. Those experiments are only made possible through slamming heavy charged atoms, or heavy ions, together at near light-speed, which can generate a droplet of primordial soup that lives for no more than a quadrillionth of a second. Scientists continue to attempt to take snapshots of this primordial soup to understand the characteristics of quark-gluon plasma.

In the attempt to identify wakes in the quark-gluon plasma, scientists have been hunting for pairings of quarks and their antimatter counterparts known as anti-quarks. When a quark races through plasma, an anti-quark should exist, travelling at precisely the same speed but in the opposite direction. Both particles, according to the hybrid model, should create detectable wakes. Sounds simple enough, but there's a fly in this soup.

"When you have two quarks produced, the problem is that, when the two quarks go in opposite directions, the one quark overshadows the wake of the second quark," Lee explained. This team realized that finding the wake of a quark would be simpler if there were no second quark obscuring it.

"We have figured out a new technique that allows us to see the effects of a single quark in the quark-gluon plasma, through a different pair of particles," Lee added.

Boson croutons

Instead of hunting for quark pairs, Lee and colleagues looked for quarks travelling in unison with a neutral elementary particle called a Z-boson, which has little effect on its surroundings. The benefit of Z-bosons is that they have a specific energy, and that makes them comparatively easy to spot.

"In this soup of quark-gluon plasma, there are numerous quarks and gluons passing by and colliding with each other," Lee said. "Sometimes when we are lucky, one of these collisions creates a Z boson and a quark, with high momentum."

In these circumstances, the quark and Z-boson should slam into each other and bounce off in opposite directions, with the quark leaving a wake, but with the Z-boson not leaving one due to its lack of impact on the surrounding quark-gluon plasma. That means any ripples spotted in this situation are made by a quark alone.

After observing 13 billion LHC collisions, Lee and the team identified around 2,000 instances in which a Z-boson was produced. During these events, the scientists consistently observed a fluid-like pattern of splashes travelling in the opposite direction of the Z bosons they detected. That, they determined, was the sought-after quark wake effect. Indeed, the patterns observed conformed to ripple-predictions made by the hybrid model of quark-gluon plasma.

"We've gained the first direct evidence that the quark indeed drags more plasma with it as it travels," Lee concluded. "This will enable us to study the properties and behavior of this exotic fluid in unprecedented detail."

The team's research was published in the journal Physics Letters B.

Astronomy isn't just about gazing at stars, it's about understanding the invisible forces that govern everything from planetary motion to the expansion of the universe. Behind every orbit, black hole, and cosmic ripple lies a theory that explains how the universe works.

This quiz dives into the foundational concepts that have revolutionized our understanding of space and time.

You'll encounter questions on gravity, general relativity, spacetime curvature, and the laws of motion that underpin celestial mechanics.

Whether you're a student of physics, a space enthusiast, or just curious about how the universe holds itself together, this quiz offers a chance to test your knowledge of the principles that shape reality.

See how well you score below!

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

The summer of 2025 brought unprecedented flash flooding across the U.S., with the central and eastern regions hit particularly hard. These storms claimed hundreds of lives across Texas, Kentucky and several other states and caused widespread destruction.

At the same time, every hurricane that formed, including the three powerful Category 5 storms, steered clear of the U.S. mainland.

Both scenarios were unusual – and they were largely directed by the polar jet stream.

What is a jet stream?

Jet streams are narrow bands of high-speed winds in the upper troposphere, around four to eight miles (seven to 13 kilometers) above the surface of the Earth, flowing west to east around the entire planet. They form where strong temperature contrasts exist.

Each hemisphere hosts two primary jet streams:

The polar jet stream is typically found near 50 to 60 degrees latitude, across Canada in the Northern Hemisphere, where cold polar air meets warmer midlatitude air. It plays a major role in modulating weather systems in the midlatitudes, including the continental U.S. With winds up to 200 mph, it's also the usual steering force that brings those bitter cold storms down from Canada.

The subtropical jet stream is typically closer to 30 degrees latitude, which in the Northern Hemisphere crosses Florida. It follows the boundary between tropical air masses and subtropical air masses. It’s generally the weaker and steadier of the two jet streams.

These jet streams act like atmospheric conveyor belts, steering storm systems across continents.

Stronger (faster) jet streams can intensify storm systems, whereas weaker (slower) jet streams can stall storm systems, leading to prolonged rainfall and flooding.

2025's intense summer of flooding

Most summers, the polar jet stream retreats northward into Canada and weakens considerably, leaving the continental U.S. with calmer weather. When rainstorms pop up, they’re typically caused by localized convection due to uneven heating of the land – picture afternoon pop-up thunderstorms.

During the summer of 2025, however, the polar jet stream shifted unusually far south and steered larger storm systems into the midlatitudes of the U.S. At the same time, the jet stream weakened, with two critical consequences.

First, instead of moving storms quickly eastward, the sluggish jet stream stalled storm systems in place, causing prolonged downpours and flash flooding.

Second, a weak jet stream tends to meander more dramatically. Its broad north-south swings in summer 2025 funneled humid air from the Gulf of Mexico deep into the interior, supplying storm systems with abundant moisture and intensifying rainfall.

This moisture surge was amplified by unusually warm conditions over the Atlantic and Gulf regions. A warmer ocean evaporates more water, and warmer air holds a greater amount of moisture. As a result, extraordinary levels of atmospheric moisture were directed into storm systems, fueling stronger convection and heavier precipitation.

Finally, the wavy jet stream became locked in place by persistent high-pressure systems, anchoring storm tracks over the same regions. This led to repeated episodes of heavy rainfall and catastrophic flooding across much of the continental U.S. The same behavior can leave other regions facing days of unrelenting heat waves.

The jet stream buffered US in hurricane season

The jet stream also played a role in the 2025 hurricane season.

Given its west-to-east wind direction, the southward dip of the jet stream – along with a weak high pressure system over the Atlantic – helped steer all five hurricanes away from the U.S. mainland.

Most of the year's 13 tropical storms and hurricanes veered off into the Atlantic before even reaching the Caribbean.

Climate change plays a role in these shifts

So, how does climate change influence the jet stream?

The strength of jet streams is controlled by the temperature contrast between the equatorial and polar regions.

A higher temperature contrast leads to stronger jet streams. As the planet warms, the Arctic is heating up at more than twice the global average rate, and that is reducing the equator-to-pole temperature difference. As that temperature gradient weakens, jet streams lose their strength and become more prone to stalling.

This increases the risk of persistent extreme rainfall events.

Weaker jet streams also meander more, producing larger waves and more erratic behavior. This increases the likelihood of unusual shifts, such as the southward swing of the jet stream in the summer of 2025.

A recent study found that amplified planetary waves in the jet streams, which can cause weather systems to stay in place for days or weeks, are occurring three times more frequently than in the 1950s.

What's ahead?

As the global climate continues to warm, extreme weather events driven by erratic behavior of jet streams are expected to become more common. Combined with additional moisture that warmer oceans and air masses supply, these events will intensify, producing storms that are more frequent and more destructive to societies and ecosystems.

In the short term, the polar jet stream will be shaping the winter ahead. It is most powerful in winter, when it dips southward into the central and even southern U.S., driving frequent storm systems, blizzards and cold air outbreaks.

You are currently making a conscious, willful decision to read this article. But physics says every action has a cause. So did you really make this decision as freely as you thought?

One of the bedrock philosophical concepts under all of physics is something called causal determinism. It says that every effect has a cause, and that if you know the current state of a system, you can use the power of physics to predict how it behaves. If effects happened without causes, then there wouldn't be much need for physics. And if we couldn't predict how systems would behave, then we wouldn't be very good at our jobs.

With this philosophy, physics has made enormous progress in advancing our understanding of the universe, from subatomic quantum systems to the Big Bang. And a part of that universe contains these weird things called brains that have the curious property of consciousness and the ability to freely make decisions.

So, at first glance, it seems like our understanding of physics forbids free will. We don't really have a choice, because if we had perfect knowledge of all the molecules and electrical activity in our brains, then we must be able to determine our choices in advance.

But there are three aspects of physics that add some wrinkles to this line of thinking.

The first is chaos theory. Some systems are easy to predict. But others, like double pendulums and weather patterns, are much harder to tackle. In these special kinds of systems, even a minuscule amount of uncertainty in the measurement of the initial state of a system very quickly compounds into complete ignorance about its future behavior. Strangely, these systems are perfectly deterministic; causes always lead smoothly to effects, so there's no mystery there. But they are impossible to predict well into the future.

The second wrinkle comes from quantum mechanics, which tells us that it's impossible to predict the outcomes of many kinds of experiments involving subatomic particles. Probabilities rule the day there, and the best we can do is assign chances to certain outcomes. Quantum mechanics is still a deterministic theory of nature — but again, it places a layer of ignorance over our understanding. We can't say for sure where a particle will go or how it will behave; we can only say what might happen. But it's not clear if the probabilistic rules of quantum mechanics apply to things like neural connections in the brain and the rise of consciousness, which is an emergent phenomenon.

The last wrinkle is exactly that: emergence. Fundamental descriptions of nature do not automatically guarantee an understanding of more complex systems. For example, we have an incredibly sophisticated theory of particle physics, based on quantum field theory, but that sophisticated theory works only when describing quantum systems. We have no quantum field theory description of how a star forms, or why chocolate tastes so good. We have to adopt other laws and theories to describe the systems as a whole.

None of these wrinkles gives a clear-cut yes-or-no answer to the question of free will. But they do show that our understanding of physics is limited. Most philosophers believe in a class of ideas under the heading of "compatibilism," which says that free will and physics can live together in harmony. It might be that our understanding of nature is not yet sophisticated enough to explain how free will can work with causal determinism.

In other words, if we work hard enough, we might someday reach a level of understanding that preserves causal determinism and all the usual physics goodness while including things like free will in a framework that makes sense.

Either way, we have no choice but to keep asking.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

The Arctic is transforming faster and with more far-reaching consequences than scientists expected just 20 years ago, when the first Arctic Report Card assessed the state of Earth's far northern environment.

The snow season is dramatically shorter today, sea ice is thinning and melting earlier, and wildfire seasons are getting worse. Increasing ocean heat is reshaping ecosystems as non-Arctic marine species move northward. Thawing permafrost is releasing iron and other minerals into rivers, which degrades drinking water. And extreme storms fueled by warming seas are putting communities at risk.

The past water year, October 2024 through September 2025, brought the highest Arctic air temperatures since records began 125 years ago, including the warmest autumn ever measured and a winter and a summer that were among the warmest on record. Overall, the Arctic is warming more than twice as fast as the Earth as a whole.

For the 20th Arctic Report Card, we worked with the National Oceanic and Atmospheric Administration, an international team of scientists and Indigenous partners from across the Arctic to track environmental changes in the North – from air and ocean temperatures to sea ice, snow, glaciers and ecosystems – and the impacts on communities.

Together, these vital signs reveal a striking and interconnected transformation underway that’s amplifying risks for people who live there.

A wetter Arctic with more extreme precipitation

Arctic warming is intensifying the region's water cycle.

A warmer atmosphere increases evaporation, precipitation and meltwater from snow and ice, adding and moving more water through the climate system. That leads to more extreme rainstorms and snowstorms, changing river flows and altering ecosystems.

The Arctic region saw record-high precipitation for the entire 2025 water year and for spring, with the other seasons each among the top-five wettest since at least 1950. Extreme weather – particularly atmospheric rivers, which are long narrow "rivers in the sky" that transport large amounts of water vapor – played an outsized role.

These wetter conditions are reshaping snow cover across the region.

Snow and ice losses accelerate warming, hazards

Snow blankets the Arctic throughout much of the year, but that snow cover isn’t lasting as long. In 2025, snowpack was above average in the cold winter months, yet rapid spring melting left the area covered by snow far smaller than normal by June, continuing a six-decade decline. June snow cover in recent years has been half of what it was in the 1960s.

Losing late spring snow cover means losing a bright, reflective surface that helps keep the Arctic cool, allowing the land instead to be directly warmed by the sun, which raises the temperature.

Sea ice tells a similar story. The year's maximum sea ice coverage, reached in March, was the lowest in the 47-year satellite record. The minimum sea ice coverage, in September, was the 10th lowest.

Since the 1980s, the summer sea ice extent has shrunk by about 50%, while the area covered by the oldest, thickest sea ice – ice that has existed for longer than four years – has declined by more than 95%.

The thinner sea ice cover is more influenced by winds and currents, and less resilient against warming waters. This means greater variability in sea ice conditions, causing new risks for people living and working in the Arctic.

The Greenland Ice Sheet continued to lose mass in 2025, as it has every year since the late 1990s. As the ice sheet melts and calves more icebergs into the surrounding seas, it adds to global sea-level rise.

Mountain glaciers are also losing ice at an extraordinary rate – the annual rate of glacier ice loss across the Arctic has tripled since the 1990s.

This poses immediate local hazards. Glacial lake outburst floods – when water that is dammed up by a glacier is suddenly released – are becoming more frequent. In Juneau, Alaska, recent outburst floods from Mendenhall Glacier have inundated homes and displaced residents with record-setting levels of floodwater.

Glacier retreat can also contribute to catastrophic landslide impacts. Following the retreat of South Sawyer Glacier, a landslide in southeast Alaska's Tracy Arm in August 2025 generated a tsunami that swept across the narrow fjord and ran nearly 1,600 feet (nearly 490 meters) up the other side. Fortunately, the fjord was empty of the cruise ships that regularly visit.

Record-warm oceans drive storms, ecosystem shifts

Arctic Ocean surface waters are steadily warming, with August 2025 temperatures among the highest ever measured. In some Atlantic-sector regions, sea surface temperatures were as much as 13 degrees Fahrenheit (7.2 Celsius) above the 1991-2020 average. Some parts of the Chukchi and Beaufort seas were cooler than normal.

Warm water in the Bering Sea set the stage for one of the year's most devastating events: Ex-Typhoon Halong, which fed on unusually warm ocean temperatures before slamming into western Alaska with hurricane-force winds and catastrophic flooding. Some villages, including Kipnuk and Kwigillingok, were heavily damaged.

As seas warm, powerful Pacific cyclones, which draw energy from warm water, are reaching higher latitudes and maintaining strength longer. Alaska's Arctic has seen four ex-typhoons since 1970, and three of them arrived in the past four years.

The Arctic is also seeing warmer, saltier Atlantic Ocean water intrude northward into the Arctic Ocean. This process, known as Atlantification, weakens the natural layering of water that once shielded sea ice from deeper ocean heat. It is already increasing sea ice loss and reshaping habitat for marine life, such as by changing the timing of phytoplankton production, which provides the base of the ocean food web, and increasing the likelihood of harmful algal blooms.

From ocean "borealization" to tundra greening

Warming seas and declining sea ice are enabling southern, or boreal, marine species to move northward. In the northern Bering and Chukchi seas, Arctic species have declined sharply – by two-thirds and one-half, respectively – while the populations of boreal species expand.

On land, a similar "borealization" is underway. Satellite data shows that tundra vegetation productivity – known as tundra greenness – hit its third-highest level in the 26-year record in 2025, part of a trend driven by longer growing seasons and warmer temperatures. Yet greening is not universal – browning events caused by wildfires and extreme weather are also increasing.

Summer 2025 marked the fourth consecutive year with above-median wildfire area across northern North America. Nearly 1,600 square miles (over 4,000 square kilometers) burned in Alaska and over 5,000 square miles (over 13,600 square kilometers) burned in Canada's Northwest Territories.

Permafrost thaw is turning rivers orange

As permafrost – the frozen ground that underlies much of the Arctic – continues its long-term warming and thaw, one emerging consequence is the spread of rusting rivers.

As thawing soils release iron and other minerals, more than 200 watersheds across Arctic Alaska now show orange discoloration. These waters exhibit higher acidity and elevated levels of toxic metals, which can contaminate fish habitat and drinking water and impact subsistence livelihoods.

In Kobuk Valley National Park in Alaska, a tributary to the Akillik River lost all its juvenile Dolly Varden and slimy sculpin fish after an abrupt increase in stream acidity when the stream turned orange.

Arctic communities lead new monitoring efforts

The rapid pace of change underscores the need for strong Arctic monitoring systems. Yet many government-funded observing networks face funding shortfalls and other vulnerabilities.

At the same time, Indigenous communities are leading new efforts.

The Arctic Report Card details how the people of St. Paul Island, in the Bering Sea, have spent over 20 years building and operating their own observation system, drawing on research partnerships with outside scientists while retaining control over monitoring, data and sharing of results. The Indigenous Sentinels Network tracks environmental conditions ranging from mercury in traditional foods to coastal erosion and fish habitat and is building local climate resilience in one of the most rapidly changing environments on the planet.

The Arctic is facing threats from more than the changing climate; it's also a region where concerns of ecosystem health and pollutants come sharply into view. In this sense, the Arctic provides a vantage point for addressing the triple planetary crisis of climate change, biodiversity loss and pollution.

The next 20 years will continue to reshape the Arctic, with changes felt by communities and economies across the planet.

In the late 1970s, legendary physicist John Wheeler proposed a radical question: Exactly when does the universe notice that we're paying attention to a quantum experiment? And does it really matter? The answer goes against everything we thought we knew.

Wheeler's thought experiment, which eventually became a real experiment, involved the famous double-slit experiment. Let's say you have a source of light and a screen with two thin, vertical slits. When you shine the light through the slits, the light acts like a wave. It interferes with itself, causing a ripple-like pattern on a far wall, with strips of brightness alternating with darkness. This is exactly how waves work, and if you ever find yourself in a harbor with two narrow openings, you'll see the waves washing up onshore with a similar pattern.

Now, let's say you make the light really weak — so weak that, eventually, only one photon at a time goes through the double slit. Amazingly, even though each individual photon acts like a particle — it hits the far wall in one specific spot — after enough photons arrive, the same interference pattern emerges. The usual conclusion is that the wave nature of a single photon interferes with itself to create the pattern.

Now, let's add one more layer. Let's say you introduce a detector to the slits, to figure out which slit the photon actually passed through on its way through the screen. When you do this, the wave nature of the photon goes away. You get to see which slit the photon passed through — but it only ever acts like a particle, and you never get an interference pattern on the far wall.

When we design a quantum experiment, we must choose to investigate either the wave nature or the particle nature of photons — but we can't do both. OK, it's weird. But so far, it's the standard sort of quantum weirdness.

Wheeler upped the ante. He asked what would happen if you were to introduce a delay. What if you were to insert a detector at the slits after the photon had already passed through?

Wheeler proposed a helpful analogy. Imagine a distant light source, like a quasar, that sends light traveling for billions of light-years. Some of that light heads right for us, while some beams follow a curved path through a gravitational lens, like a massive cluster. Both beams arrive on Earth at the same time, and we can set up an experiment to interfere with those beams. In that experiment, we can choose to study either the wave nature or the particle nature of light.

Wheeler guessed the answer. He was right, and his correctness was later borne out by experiments. Even when we make a delayed choice, the photons somehow keep track of that and alter whether they're going to make an interference pattern.

How does this work? We're making our choice at the final leg of the light's journey. How did the photons "know" what choice we were going to make ahead of time? It seems as if our choice in the future went back in time to alter how the photons behaved in the past.

An updated version of the experiment, known as the "delayed choice quantum eraser," makes this even crazier. In this experiment, the photons pass through the slits. Then, the experiment decides whether to monitor the slits. Well after the photons have struck the screen, the experimenter decides to read the information. If the experimenter reads the information about which slit the photon passed through, there will never be an interference pattern. If the experiment throws away the information, an interference pattern emerges.

Remember, all of this is after the photon has already hit the screen.

Wheeler taught us how to think about this. He argued that it doesn't make sense to talk about photons "in flight." We only have measurements and observations — the final results of our experiments. The order of the events and what happened during the experiment itself don't matter. Photons aren't really in flight in the way we think of it, and the wave-particle duality of photons doesn't make sense in the way we usually think about things.

What we get, whether particles or waves, is what we get. And it's only once we make that measurement that nature reveals what aspect of reality to show us.

When it comes to greenhouse gas emissions, carbon dioxide gets the lion's share of global attention.

But methane is the second-largest contributor to human-caused global warming. A high proportion of methane emissions comes from the energy sector, often from concentrated "point sources" such as flare stacks, coal vents and open-pit mines. To help reduce those emissions, we must first identify the major culprits — and new satellite data is helping us do just that.

Using high-resolution observations from the GHGSat satellite constellation, researchers have produced a global, facility-level view of methane emissions, identifying thousands of individual oil, gas and coal sites that are releasing the greenhouse gas into Earth's atmosphere.

"This is the first global gridded estimate of annual methane emissions from facility-scale measurements, an advancement in measurement-based accounting that is due to the comprehensive scale of GHGSat's satellite constellation to measure methane worldwide," said Dylan Jervis of GHGSat Inc., lead author of a new study on the findings published Dec. 11 in the journal Science.

"This information will be useful to improve understanding and predictions of methane emissions, and, therefore, provide information that is useful to direct mitigation efforts," Jervis told Space.com.

Traditionally, scientists have measured methane emissions with a mix of bottom-up inventories, which estimate emissions based on industry activity but can miss short-term fluctuations like leaks, and top-down atmospheric measurements, which detect methane concentrations directly but lack the resolution to pinpoint specific sources. Neither can paint a very precise picture of global methane emissions from the energy sector. But the GHGSat constellation, run by the Canadian company GHGSat, bridges that gap by combining meter-scale spatial resolution with global coverage.

Analyzing GHGSat observations of methane plumes collected in 2023, the team estimated annual methane emissions from 3,114 oil, gas and coal facilities worldwide that totaled about 9 million tons (8.3 million metric tons) per year.

Geographically, the biggest emitters stood out clearly in the satellite data. "The countries where we measure the largest oil and gas methane emissions are Turkmenistan, the U.S., Russia, Mexico and Kazakhstan," said Jervis. "The countries where we measure the large coal emissions are China and Russia."

While bottom-up inventories are fairly good at estimating methane emissions on such large scales as countries, they aren't nearly as precise when you zoom in. "We found moderate agreement between GHGSat-measured emission estimates and bottom-up inventory predictions at the country level, but very little agreement at 0.2 degree x 0.2 degree [about 20 by 20 kilometers] spatial resolution," Jervis said. Thus, effective change may need to happen at the facility level, not at the country level.

The researchers tracked how often individual facilities emitted detectable methane plumes, a metric they call persistence.

"Persistence of emissions depends more on sector than region," said Jervis. For coal facilities, methane plumes were detected about half the time on average. Oil and gas sites, by contrast, were far more intermittent, emitting detectable methane in only about 16% of satellite observations on average. That variability makes oil and gas emissions especially difficult to capture with infrequent monitoring.

For the most accurate and actionable methane estimates, detailed surveys like the ones provided by GHGSat are crucial — which is why GHGSat is growing its constellation. Two new satellites were launched in June, and two more in November, bringing the company's total to 14 satellites. "This will enable better coverage, both spatially and temporally, allowing us to detect more emissions and monitor them more frequently," said Jervis.

Scientists have inched a step closer to solving an enduring mystery in physics — why the universe contains any matter at all — thanks to a newly combined analysis from two of the world's leading neutrino experiments.

By pooling nearly 16 years of measurements, the NOvA experiment in the United States and the T2K experiment in Japan have produced the most precise picture yet of how neutrinos and their antimatter twins transform as they travel. The results, published on Oct. 22 in the journal Nature, sharpen the search for subtle differences in how these particles behave — differences that may help explain why matter prevailed over antimatter in the early universe.

If the two are perfectly symmetric, according to the Standard Model of particle physics, the Big Bang should have created equal amounts of matter and antimatter nearly 14 billion years ago. And in fact, because matter and antimatter annihilate on contact, a perfectly balanced universe should have ended in a wash of pure energy. Yet, today's cosmos is overwhelmingly made up of matter, suggesting some subtle mechanism gave matter a slight and still-mysterious advantage early on.

A prime suspect for tipping the scales is the neutrino, a ghostly, almost massless particle that permeates the universe but rarely interacts with anything. This is why scientists often refer to them as "ghost particles." Physicists have long wondered whether neutrinos and antineutrinos behave differently in ways experiments can detect. Even a subtle mismatch, known as CP violation, could illuminate how matter gained its cosmic edge.

"While there is still more to understand, the critical experimental question is clear: can we see this symmetry violation in neutrinos, and if so, how big is it?" Ryan Patterson, a physics professor at the California Institute of Technology and co-lead of the NOvA team, told Space.com.

Neutrinos change 'flavor'

Part of what makes neutrinos so elusive — and so intriguing — is their ability to change identity. They exist in three "flavors," and as they move through space, they oscillate among these types because each flavor is a blend of three mass states. As neutrinos travel, those underlying mass states shift, causing the particles to morph from one flavor to another.

"If you think of the flavors as being like strawberry, chocolate and vanilla, this would be like finding your strawberry ice cream cone turned to chocolate on your way home," a recent Caltech statement explains.

By tracing these flavor changes, scientists can measure the tiny mass differences that govern neutrino oscillations — and by comparing neutrinos with antineutrinos behaviors, they can probe CP violation.

To do this, the NOvA experiment (short for NuMI Off-axis ν_e Appearance) fired a beam of neutrinos from Fermilab near Chicago to a detector 500 miles (800 kilometers) away in Minnesota. Across the Pacific, Japan's T2K (short for Tokai-to-Kamioka) experiment sent its own beam 183 miles (295 kilometers) from the Japan Proton Accelerator Research Complex in Tokai to the massive Super-Kamiokande detector, buried 0.6 miles (about 1 kilometer) beneath a mountain in Kamioka.

Because the experiments operate at different distances and energies, each captures complementary features of neutrino oscillations. Combining their data allows researchers to isolate the subtle parameters that control how neutrinos transform.

A key result of the joint analysis is a sharply refined measurement of one of the most fundamental oscillation parameters, known as the neutrino mass splitting. The collaboration has now constrained this value to just 2 percent, making it one of the most precise measurements ever reported.

"It underlies all the other measurements we make," Patterson said. He added that this progress also opens up avenues to determine the neutrino mass hierarchy, the still-unknown ordering of the three neutrino mass states.

"As of today, we accept the existence of three neutrino families, each associated with distinct masses," Federico Sanchez, an experimental physicist specializing in neutrino physics and a longtime T2K collaborator, told Space.com. "But we still lack a fundamental understanding of why there are precisely three, not two, four or more — and why their mass differences take the specific values we observe."

"The mass hierarchy is not only a cornerstone for many theoretical calculations and predictions but also provides a tangible result that can be directly compared with existing models," he added.

The mass hierarchy affects how neutrinos and antineutrinos oscillate differently — a key part of the search for CP violation. In what is called normal hierarchy, one of the three known neutrino "flavors," muon neutrinos, transform into electron neutrinos more readily than their antimatter counterparts, muon antineutrinos, transform into electron antineutrinos. In the inverted hierarchy, that pattern flips.

The new joint analysis isn't able to say which hierarchy nature prefers. But if future data show the hierarchy is inverted, Patterson says the current dataset already hints that neutrinos may violate CP symmetry. If that data show the normal hierarchy is correct, even more data will be needed to tease apart the competing effects.

"Neutrino physics is a strange field. It is very challenging to isolate effects," Kendall Mahn, a professor at Michigan State University and T2K co-spokesperson, said in the Caltech statement. "Combining analyses allows us to isolate one of these effects, and that's progress."

A new shared 'language' for neutrino science

Beyond the immediate physics results, researchers say one of the collaboration's most significant achievements is the development of an initial common framework — a shared "language" for how neutrino interactions are described across experiments.

Although all experiments are grounded in the same underlying physics, each makes different approximations and methodological choices based on its unique detector design. Among the most critical assumptions are those involving how neutrinos interact with matter, which is essential for accurately reconstructing their energy, and how many neutrinos are produced at a given energy, said Sanchez.

Even small differences in these models can affect the interpretation of oscillation patterns, he noted. By harmonizing these assumptions, the collaboration has created a starting template that future experiments can adopt to ensure their findings are directly comparable.

"Precision in these measurements is critical, as even subtle discrepancies could signal deviations from the model — potentially revealing new physics," Sanchez told Space.com. "The more precise the agreement is the more confident we are that our description is correct."

The timing couldn’t be better. Scientists say such a unified framework will be essential for the next generation of ultra-sensitive experiments — the Deep Underground Neutrino Experiment (DUNE) in Illinois and South Dakota, and the Hyper-Kamiokande in Japan — are under construction and expected to begin operations in 2028. These next-generation detectors will perform measurements far more sensitive than NOvA or T2K, potentially offering definitive evidence of CP violation in the next decade.

And if neutrinos truly do treat matter and antimatter differently, scientists may finally uncover the long-sought reason the universe exists in the form we know today.

A study about these results was published on Oct. 22 in the journal Nature.

We've all had the thought — wouldn't it be nice if summer were just a little longer? Well, it might become a reality in the not-too-distant future. And, unfortunately, that's not a good sign for our planet.

According to a new study, climate change — primarily driven by human activities like burning coal for cheap power — could lengthen summers in Europe by 42 days by the year 2100. That's because the "latitudinal temperature gradient" (LTG), or the temperature difference between the North Pole and the equator, is currently decreasing. A higher LTG drives wind patterns across the Atlantic Ocean, bringing about seasonal temperature changes in Europe. With a lower LTG, summer weather patterns and heat waves will last longer across the continent.

"Our findings show this isn't just a modern phenomenon; it's a recurring feature of Earth’s climate system. But what's different now is the speed, cause and intensity of change," Dr. Laura Boyall, an author of the study, said in a statement."

To peer back into Earth's climate history in Europe, researchers analyzed layers of mud at the bottom of lakes. Deposited seasonally, these sediments paint a clear timeline of winters and summers as far back as 10,000 years ago.

Around 6,000 years ago, European summers were about eight months long due to natural fluctuations in the LTG. But now, the Arctic is warming up to four times faster than the global average, in part due to greenhouse gas emissions. For every degree Celsius the LTG decreases, European summers will grow by about six days. Thus, according to current climate projections, Europe will have 42 extra days of summer by 2100.

"Our research has uncovered that European seasons have been driven by the temperature gradient over thousands of years, which provides useful insight that can be used to help predict future changes more accurately," says Dr. Celia Martin-Puertas, lead researcher from Royal Holloway at the University of London. "The findings underscore how deeply connected Europe’s weather is to global climate dynamics and how understanding the past can help us navigate the challenges of a rapidly changing planet."

A study on the research was published on Nov. 19 in the journal Nature Communications.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

The nature of time has plagued thinkers for as long as we've tried to understand the world we live in. Intuitively, we know what time is, but try to explain it, and we end up tying our minds in knots.

St. Augustine of Hippo, a theologian whose writings influenced western philosophy, captured a paradoxical challenge in trying to articulate time more than 1,600 years ago:

"What then is time? If no one asks me, I know; if I want to explain it to a questioner, I do not know."

Nearly a thousand years earlier, Heraclitus of Ephesus offered a penetrating insight. According to classical Greek philosopher Plato’s Cratylus:

"Heraclitus is supposed to say that all things are in motion and nothing at rest; he compares them to the stream of a river, and says that you cannot go into the same water twice."

Superficially, this can sound like another paradox — how can something be the same river and yet not the same? But Heraclitus adds clarity, not confusion: the river — a thing that exists — continuously changes. While it is the same river, different waters flow by moment to moment.

While the river's continuous flux makes this plain, the same is true of anything that exists — including the person stepping into the river. They remain the same person, but each moment they set foot in the river is distinct.

How can time feel so obvious, so woven into the fabric of our experience, and yet remain the bane of every thinker who has tried to explain it?

An issue of articulation

The key issue isn't one most physicists would even consider relevant. Nor is it a challenge that philosophers have managed to resolve.

Time itself isn't difficult to grasp: we all understand it, despite our persistent struggle to describe it. As Augustine sensed, the problem is one of articulation: a failure to precisely draw the right boundaries around the nature of time both conceptually and linguistically.

Specifically, physicists and philosophers tend to conflate what it means for something to exist and what it means for something to happen — treating occurrences as if they exist. Once that distinction is recognized, the fog clears and Augustine's paradox dissolves.

The source of the issue

In basic logic, there are no true paradoxes, only deductions that rest on subtly mishandled premises.

Not long after Heraclitus tried to clarify time, Parmenides of Elea did the opposite. His deduction begins with a seemingly valid premise — "what is, is; and what is not, is not" — and then quietly smuggles in a crucial assumption. He claims the past is part of reality because it has been experienced, and the future must also belong to reality because we anticipate it.

Therefore, Parmenides concluded, both past and future are part of "what is," and all of eternity must form a single continuous whole in which time is an illusion.

Parmenides' pupil, Zeno, devised several paradoxes to support this view. In modern terms, Zeno would argue that if you tried walking from one end of a block to the other, you'd never get there. To walk a block, you must first walk half, then half of what remains, and so on — always halving the remaining distance, never reaching the end.

But of course you can walk all the way to the end of the block and beyond — so Zeno's deduction is absurd. His fallacy lies in removing time from the picture and considering only successive spatial configurations. His shrinking distances are matched by shrinking time intervals, both becoming small in parallel.

Zeno implicitly fixes the overall time available for the motion — just as he fixes the distance — and the paradox appears only because time was removed. Restore time, and the contradiction disappears.

Parmenides makes a similar mistake when claiming that events in the past and future — things that have happened or that will happen — exist. That assumption is the problem: it is equivalent to the conclusion he wants to reach. His reasoning is circular, ending by restating his assumption — only in a way that sounds different and profound.

Space-time models

An event is something that happens at a precise location and time. In Albert Einstein's theories of relativity, space-time is a four-dimensional model describing all such occurrences: each point is a particular event, and the continuous sequence of events associated with an object forms its worldline — its path through space and time.

But events don't exist; they happen. When physicists and philosophers speak of space-time as something that exists, they're treating events as existent things — the same subtle fallacy at the root of 25 centuries of confusion.

Cosmology — the study of the whole universe — offers a clear resolution.

It describes a three-dimensional universe filled with stars, planets and galaxies that exist. And in the course of that existence, the locations of every particle at every instance are individual space-time events. As the universe exists, the events that happen moment by moment trace out worldlines in four-dimensional space-time — a geometric representation of everything that happens during that course of existence; a useful model, though not an existent thing.

The resolution

Resolving Augustine's paradox — that time is something we innately understand but cannot describe — is simple once the source of confusion is identified.

Events — things that happen or occur — are not things that exist. Each time you step into the river is a unique event. It happens in the course of your existence and the river's. You and the river exist; the moment you step into it happens.

Philosophers have agonized over time-travel paradoxes for more than a century, yet the basic concept rests on the same subtle error — something science fiction writer H.G. Wells introduced in the opening of The Time Machine.

In presenting his idea, the Time Traveller glides from describing three-dimensional objects, to objects that exist, to moments along a worldline — and finally to treating the worldline as something that exists.

That final step is precisely the moment the map is mistaken for the territory. Once the worldline, or indeed space-time, is imagined to exist, what’s to stop us from imagining that a traveller could move throughout it?

Occurrence and existence are two fundamentally distinct aspects of time: each essential to understanding it fully, but never to be conflated with the other.

Speaking and thinking of occurrences as things that exist has been the root of our confusion about time for millennia. Now consider time in light of this distinction. Think about the existing things around you, the familiar time-travel stories and the physics of space-time itself.

Once you recognize ours as an existing three-dimensional universe, full of existing things, and that events happen each moment in the course of that cosmic existence — mapping to space-time without being reality — everything aligns. Augustine's paradox dissolves: time is no longer mysterious once occurrence and existence are separated.

Interplanetary dust laced with helium-3 that has settled on the sea floor has provided climate scientists with an urgently needed historical record of sea ice. That urgency stems from climatologists battling with understanding how the Arctic will respond to the worsening climate crisis.

The amount of ice on the Arctic Ocean has depleted by more than 42% in response to rising temperatures since regular satellite monitoring began in 1979 — and the Arctic continues to warm faster than anywhere else on Earth, particularly due to human-driven global warming caused by things like burning coal for cheap power. In a few decades time we could see the Arctic Ocean free of ice all summer long. Besides the resultant rising sea levels as the ice melts, scientists want to learn more about how this change in sea ice affects the habitability of the Arctic and the wider world.

"If we can project the timing and spatial patterns of ice coverage decline in the future, it will help us understand warming, predict changes to food webs and fishing, and prepare for geopolitical shifts," said Frankie Pavia of the University of Washington in a statement.

Until now, it has been difficult to make accurate predictions about the Arctic sea ice in part because there have been no historical records to base predictions on. If we don't know how the sea ice responded to changes in climate in the past, we can't say for certain how it will respond in the future.

Which is where the cosmic dust comes in.

We are being gently doused in dust from space every day. If you place a bowl outside for a week, some of the dirt that gathers in it will be from space.

When the Arctic Ocean is covered in ice, the dust is prevented from reaching the sea floor. So when the ocean is largely absent of ice, more of the cosmic dust is able to settle as sediment.

Pavia led a team who went searching for this dust in sedimentary cores taken from three locations in the Arctic Ocean: one near the North Pole where there is ice present all year, one near the edge of the ice in September when ice coverage is at its annual lowest, and another at a site that was covered in ice in 1980, but no longer is.

In particular, Pavia's team was looking for sedimentary layers of the isotopes helium-3 and thorium-230. Each has a different origin. Helium-3 is present in cosmic dust, having been captured by dust grains from the sun's solar wind, whereas thorium is a decay product of naturally occurring uranium that has become dissolved in the ocean. At times of high ice abundance on the ocean, the ratio of thorium-230 to helium-3 should be higher than at times when there is less ice and more cosmic dust can reach the seabed.

"It's like looking for a needle in a haystack," said Pavia. "You've got this small amount of cosmic dust raining down everywhere, but you've also got Earth sediments accumulating pretty fast."

The cores provided a historical record chronicling periods when greater and smaller amounts of cosmic dust have reached the bottom of the ocean, corresponding to differing amounts of sea ice. The ice has waxed and waned over millennia, and the cores indicate that the dawn of the most recent ice age, beginning about 20,000 years ago, saw a decrease in the amount of cosmic dust on the seabed as ice covered the entirety of the Arctic all year round.

"During the last ice age there was almost no cosmic dust in the Arctic sediments," said Pavia.

When the ice began to melt and retreat as the ice age started to come to an end 15,000 years ago, the cores show that the amount of cosmic dust in the sediment on the sea floor began to increase.

What's most intriguing is what the cores tell us about what governs the amount of sea ice and how its presence, or lack thereof, can influence the balance of nutrients and hence the biosphere of the ocean.

The assumption had been that the loss of ice from the Arctic Ocean was governed by the temperature of the ocean, but the results from Pavia's group indicate that it has more to do with atmospheric temperatures instead. This is a crucial piece of information because the ocean takes longer to respond to climate change than the atmosphere. If true, then we may lose sea ice in the Arctic Ocean more quickly than we expected.

They also found that sea-ice coverage is correlated with how quickly nutrients in the ocean are consumed by biological processes. Tiny shells that were once worn by microbes called foraminifera were present in the cores, and a chemical analysis revealed how much of the total available nutrients they consumed when the microbes were alive at different points in the historical record. Pavia’s team found a correlation between increased consumption of nutrients and a lack of sea ice.

"As ice decreases in the future, we expect to see increased consumption of nutrients by phytoplankton in the Arctic, which has consequences for the food web," said Pavia. Long term, such productivity might not be maintained, causing delicate ecosystems both in the ocean and on the coast to collapse.

The results still leave some questions unanswered for now, such as why nutrient availability changes with the amount of sea ice present. One possible explanation is that with less ice, there is more room on the surface of the ocean for photosynthesizing algae that produce more nutrients. However, a competing effect would be the dilution of the nutrients by the melting sea ice, meaning there must be a delicate balance between the two processes.

The results were published on Nov. 6 in the journal Science.

Earth just endured one of its most extreme wildfire years on record — and scientists say human-driven climate change is the cause.

A sweeping new analysis, the State of Wildfires 2024–25 report, finds that human-driven global warming dramatically increased the intensity and scale of wildfires across the globe, in some regions making severe fire seasons 25 to 35 times more likely than they would have been in a cooler world.

The international study combines satellite data, weather reanalysis and land-surface models to show how heat, drought and vegetation changes converged into record-breaking fires from the Amazon to California.

"Land surface models simulate how climate, vegetation and fire interact across the Earth’s surface," Douglas Kelley, a land surface modeler at the U.K. Center for Ecology & Hydrology (UKCEH) and a co-lead of the State of Wildfires annual report, told Space.com. Kelley and his collaborators used two approaches to study the impacts of global wildfires, first running thousands of simulations of past fire seasons with and without the effects of human-driven climate change. Then, they looked at models of the Earth's vegetation to see how the growth and death of plants can produce fuel for wildfires. "Together, these approaches show both how climate change has already influenced major fire events, and what the future might hold,” Kelley said.

The team calculated that, from March 2024 through February 2025, wildfires burned 1.4 million square miles (3.7 million square kilometers), an area larger than the size of India.

Certain regions saw truly staggering spikes. Fire emissions were higher than normal, with Bolivia seeing its highest carbon dioxide emissions total of this century (771 million tons), while Canada had its second year of reaching over a billion tons its CO2 emissions. Brazil's Pantanal region, considered the world's largest wetland, had six times the average carbon dioxide emissions for the area.

As carbon dioxide helps contribute to greenhouse gases in our atmosphere, these emission increases are helping to propel a positive feedback loop, driving up global warming conditions even further, which, in turn, can lead to more extreme wildfires.

The most powerful finding for the team was how clear climate change emerged as a variable in driving the intensity of the wildfire seasons worldwide.

"Wildfires are shaped by a tangled mix of weather, vegetation, land use and chance — factors that usually make event-scale attribution incredibly difficult. To fully reflect that complexity, we pushed our methods to explore thousands of different ways that climate, people, and ecosystems might interact to influence fire," Kelley said.

"Yet across all those possibilities, the conclusion barely wavered: human-driven climate change increased the likelihood of these extreme fires and amplified how much land burned...The science has now advanced to the point where the climate signal is unmistakable. But worryingly, climate change itself has advanced so far that this signal is visible in every extreme fire event we assessed,” Kelley said.

The human and ecological toll

Wildfires in 2024 and 2025 killed more than 200 people worldwide, including 100 people in Nepal, 34 people in South Africa and 30 people in Los Angeles. The Southern California blazes alone forced 150,000 evacuations and caused an estimated $140 billion in damages. Similarly, fires in Canada's Jasper National Park alone cost over US $1 billion in damages while Brazil's Pantanal’s agribusiness sector lost over $200 million due to wildfires.

Besides carbon emissions, air quality impacts were also significant. Fine particulate pollution from fires in Brazil reached up to 60 times higher than the World Health Organization’s safe limits, exposing hundreds of millions of people to toxic smoke.

Watching the Earth burn from space

For scientists, much of this evidence comes from low-Earth orbit. Satellites such as NASA's Terra and Aqua satellites have become indispensable for detecting active fires, mapping burn scars and monitoring atmospheric pollution from smoke plumes.

Those space-based observations fed directly into the State of Wildfires analysis, which used them to validate fire-weather models and quantify how much climate change has altered conditions on the ground.

The research team says future versions of the report will rely even more heavily on upcoming hyperspectral sensors and next-generation Earth observation satellites, which can track vegetation dryness, fuel loads and even early-stage ignition events in near real time.

For researchers like Kelley, the question then becomes: what can humanity do about it?

"We touch on this in our summary for policymakers, especially around climate finance and how wildfires affect nature-based climate solutions. However, we haven’t yet been in a position to explore in depth how local fire management decisions influenced each event: what worked, what didn’t, and what we can learn. Advances in scientific methods and ongoing study time will enable us to do this, and it's a key area for future work," said Kelley.

Imagine a particle so ghostly that over 100 trillion of them could pass through you every single second without you noticing anything at all. Spooky, right? Well, believe it or not, these particles, called "neutrinos," not only exist, but they are so abundant that they are the second most common particle in the universe (after photons, the particles that make up light).

So, you might not get visited by a phantom this Halloween, but you'll definitely encounter plenty of cosmic ghost neutrinos, yet you won't notice a single thing. In fact, you're encountering them right now.

The ethereal nature of neutrinos, understandably nicknamed "ghost particles," means that despite how common they are, and the fact we are being constantly pelted with trillions of them, scientists haven't been able to get a good handle on many of their characteristics. For instance, their masses are shrouded in mystery. That is troubling because the sheer abundance of neutrinos in the observable universe — , about 10 to the power 87 (or 10 followed by 86 zeroes) — means they must have played a key role in the development of the cosmos even though they rarely interact with other particles of matter.

For example, scientists theorize that neutrinos were vitally important in the process that led to matter vastly outweighing antimatter in the universe. Antimatter and matter should have been created in equal amounts by the Big Bang — shouldn't they be perfectly symmetrical because they're made of the same particle components, just with opposite charges? — it is perplexing how one came to rule over the other. And, because when matter and antimatter counterparts meet, they annihilate each other; if it weren't for the process that gave matter the upper hand, the universe may have been devoid of matter altogether.

Like the Scooby-Doo-gang approaching another haunted mansion or abandoned funfair, scientists are determined to get to the bottom of this cosmic ghost story. As you might imagine, even though neutrinos are created by a wealth of cosmic events like stars and supernovas and even nuclear reactors here on Earth, the fact that they are virtually massless, chargeless and traverse the cosmos at near the speed of light means detecting them is much harder than nabbing Mr. Carswell the corrupt bank manager or dastardly museum curator Mr. Wickles.

However, just like Fred, Velma, Daphne, Shaggy and Scooby always come together to remove another rubber fright mask and expose a spooky crook, selected scientists have gathered via 2025's Science Policy & Advocacy for Research Competition (SPARC) to solve the mystery of these cosmic phantoms. Lasting 10 weeks, the SPARC seminar series aims to equip scientists with essential skills in science policy and communication, helping them translate complex research into clear messages for nontechnical audiences.

And neutrinos really fit the bill.

"I've always been fascinated by how we extract information from reality — even when we can’t fully define what reality is," Karim Hassinin, a Ph.D. candidate at the University of Houston and SPARC participant, said in a statement. "Theory, at its core, is a kind of storytelling, and every model is just one way of seeing the world. Through this program, I hope to learn how to translate those complex layers of scientific reasoning into stories that anyone can understand — so people can see not just the data, but the wonder behind discovery."

Hassinin is behind a new way to think about neutrinos, developed as a result of teaching an undergraduate physics class and seeing that his students had different perspectives on these cosmic phantoms. He is bringing that new approach to SPARC and, through it, to a wider general audience.

"The technical details will always be there, but it’s essential to show people the purpose of science and how it shapes our world," Hassinin said. "Our daily lives depend on technology, and technology depends on science. Through SPARC, I’ve gained a new perspective on how vital it is to bridge the gap between complex research and public understanding — because science communication truly matters everywhere."

In terms of his research, Hassinin uses computer simulations to investigate how neutrinos work their ghostly magic as they pass through different types of materials.

"We tell the generator how many neutrinos we want to use, what type of neutrino, and what material we want the neutrino to interact with," Hassinin explained. "Without neutrino interactions, we don't know anything about neutrinos. We have to understand something deeply before we can understand how to apply it."

Meghna Bhattacharya, a Postdoctoral Research Associate at Fermi National Accelerator Laboratory (Fermilab), is another scientist hot on the trail of neutrinos, focusing on algorithms that could identify neutrinos ejected into the universe when massive stars reach the end of their lives and go supernova.

Bhattacharya's work is set to play a key role in helping to develop the Deep Underground Neutrino Experiment (DUNE), two neutrino detectors placed in an intense beam of trillions of neutrinos currently under development near Fermilab, Illinois, and a far detector at the Sanford Underground Research Facility (SURF), South Dakota.

"These tools are designed to be integrated into DUNE, contributing to major questions about the universe’s evolution while also advancing computational techniques in physics," Bhattacharya said. "The tools being developed to answer fundamental science questions often lead to broader real-world applications. For example, technologies like proton beams, originally used in particle physics, are now being used for cancer treatment."

For Bhattacharya, the appeal of SPARC is the opportunity to share the story of her research with a wider audience and to make this audience aware of its wider impact on society.

"Looking forward, I hope to grow as a communicator and advocate for science more effectively, not only to learn how to distill complex research into accessible narratives but also to pass down the excitement of my research," she concluded.

2024 may have been Earth's hottest year in at least 125,000 years, according to a grim climate report published Wednesday (Oct. 29) that describes our world as "on the brink" and warns its "vital signs are flashing red," with nearly two-thirds showing record highs.

Last year had already been declared the hottest on record (those records dating back to the late 1800s), following 2023 — which used to be considered the warmest year in human history. The year 2024 also capped a decade of record-breaking heat fueled by human-caused climate change, continuing a trend that began in 2015. Now, the new report, led by researchers at Oregon State University, suggests the year was also likely hotter than the peak of the last interglacial period, roughly 125,000 years ago, when natural shifts in Earth's orbit and tilt made the planet warmer and sea levels several meters higher. That result is based on previously published climate studies.

The study concludes that 22 of 34 measurable indicators of Earth's health, including greenhouse gas levels, ocean heat, sea ice and deforestation, have reached record extremes. The authors warn that these trends suggest humanity is in a "state of ecological overshoot," consuming the planet's resources faster than they can be replenished.

"The message is simple in that the climate crisis has entered an emergency phase and every tenth of a degree of avoided warming matters," William Ripple, a professor of ecology at Oregon State University who co-led the new report, told Space.com. "We need courage, cooperation and speed."

Published in the journal BioScience, the report shows that planet-warming gases such as carbon dioxide and methane reached record levels again in 2025, with carbon-dioxide concentrations at Hawaii's Mauna Loa Observatory surpassing 430 parts per million in May — a level likely unseen in millions of years.

According to the researchers, the ongoing warming stems from a combination of a few things.

For one, there are fewer sunlight-reflecting aerosols in the atmosphere, such as sulfates from industrial pollution, allowing heat to build up. These aerosols also influence how clouds form and reflect light; as temperatures rise, clouds are becoming thinner and less reflective, trapping more heat. Our planet is darkening too, as Earth's reflectivity, or albedo, is dropping to near-record lows due to melting ice and reduced snow cover that expose darker surfaces that absorb even more heat. Recent research has shown the Northern Hemisphere is darkening faster than the South, creating an imbalance that scientists say is rising faster than models predicted, and could intensify warming in the northern hemisphere and disrupt global weather patterns.

The effects of these trends are visible across the planet, including in all-time high ocean heat, which fueled the largest coral-bleaching event ever recorded, according to the National Oceanic and Atmospheric Administration. Greenland and Antarctic ice masses are now at record lows, with loss rates quadrupling since the 1990s — evidence, the report notes, that both regions may have already crossed critical tipping points that could lock in several meters of future sea-level rise.

Forests, too, are under stress. Studying satellite data, Ripple's team found that global tree-cover loss reached 29.6 million hectares in 2024, the second-highest total on record and nearly 5% higher than what was seen in 2023. Fire-related losses surged 370% over the course of 2023, fueled by hotter, drier conditions driven by human-induced climate change and El Niño, the researchers found.

These trends illustrate that nature's built-in safety nets against climate change, such as forests, soils and other ecosystems that capture and store carbon, regulate nutrients, and buffer against environmental extremes are "starting to falter," Ripple said.

By August 2025, the European Union had endured its most extensive wildfire season on record — the fires burned more than 1 million hectares — and Canada faced its second-largest fire season. As fires burn, they release massive amounts of carbon into the atmosphere, heating the planet and increasing the risk of even more fires — a dangerous, self-reinforcing cycle of warming, the study warns.

"It's difficult to pinpoint thresholds where climate tipping points are crossed and changes may become irreversible," Ripple said, "but it's increasingly clear that even current levels of warming could destabilize the Earth system."

Brazil's Amazon — which holds about 60% of the world's largest tropical forest — is one of the few bright spots in the report. Deforestation there fell by about 30% in 2024, reaching its lowest level in nine years, thanks to "strengthened environmental enforcement under President Luiz Inácio Lula da Silva's administration, which has prioritized conservation efforts," , the authors note.

The team's findings align with another major climate assessment released earlier this month. That report, authored by 160 scientists from 87 institutions in 23 countries, warns that warm-water coral reefs that support nearly a billion people and a quarter of all marine life are crossing their tipping point, as evidenced by mass die-offs already under way. The report also flags looming tipping points for the Amazon rainforest, polar ice sheets, and key ocean currents that help regulate Earth's climate.

"The findings of this report are incredibly alarming," Mike Barrett, a chief scientific advisor at the World Wildlife Fund in the U.K. who co-authored the report, said in a statement. "That warm-water coral reefs are passing their thermal tipping point is a tragedy for nature and the people that rely on them for food and income."

The twin reports arrive just weeks before the United Nations climate summit in Brazil, where scientists hope their findings will push world leaders to take stronger action against these cascading threats.

"As we head into the COP30 climate negotiations it's vital that all parties grasp the gravity of the situation and the extent of what we all stand to lose if the climate and nature crises are not addressed," Barrett said in the statement. "The solutions are within our reach — countries must show the political bravery and leadership to work together and achieve them."

Both reports stress that solutions exist, and there is still time to act. Rapidly scaling renewable energy, especially solar and wind, "is likely the single most powerful lever," Ripple said.

When asked what gives him hope that humanity can still avoid the worst outcomes described in the report, "hope comes from nature's resilience and human ingenuity," he said. "Earth systems can recover if given the chance."

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Hurricanes are America's most destructive natural hazards, causing more deaths and property damage than any other type of disaster. Since 1980, these powerful tropical storms have done more than US$1.5 trillion in damage and killed more than 7,000 people.

The No. 1 cause of the damages and deaths from hurricanes is storm surge.

Storm surge is the rise in the ocean's water level, caused by a combination of powerful winds pushing water toward the coastline and reduced air pressure within the hurricane compared to the pressure outside of it. In addition to these factors, waves breaking close to the coast causes sea level to increase near the coastline, a phenomenon we call wave setup, which can be an important component of storm surge.

Accurate storm surge predictions are critical for giving coastal residents time to evacuate and giving emergency responders time to prepare. But storm surge forecasts at high resolution can be slow.

As a coastal engineer, I study how storm surge and waves interact with natural and human-made features on the ocean floor and coast and ways to mitigate their impact. I have used physics-based models for coastal flooding and have recently been exploring ways that artificial intelligence can improve the speed of storm surge forecasting.

How storm surge is forecast today

Today, operational storm surge forecasts rely on hydrodynamic models, which are based on the physics of water flow.

These models use current environmental conditions – such as how fast the storm is moving toward shore, its wind speed and direction, the timing of the tide, and the shape of the seafloor and the landscape – to compute the projected surge height and determine which locations are most at risk.

Hydrodynamic models have substantially improved in recent decades, and computers have become significantly more powerful, such that rapid low-resolution simulations are possible over very large areas. However, high-resolution simulation that provide neighborhood-level detail can take several hours to run.

Those hours can be critical for communities at risk to evacuate safely and for emergency responders to prepare adequately.

To forecast storm surge across a wide area, modelers break up the target area into many small pieces that together form a computational grid or mesh. Picture pixels in an image. The smaller the grid pieces, or cells, the higher the resolution and the more accurate the forecast. However, creating many small cells across a large area requires greater computing power, so forecasting storm surge takes longer as a result.

Forecasters can use low-resolution computer grids to speed up the process, but that reduces accuracy, leaving communities with more uncertainty about their flood risk.

AI can help speed that up.

How AI can create better forecasts

There are two main sources of uncertainty in storm surge predictions.

One involves the data fed into the computer model. A hurricane's storm track and wind field, which determine where it will make landfall and how intense the surge will be, are still hard to forecast accurately more than a few days in advance. Changes to the coast and sea floor, such as from channel dredging or loss of salt marshes, mangroves or sand dunes, can affect the resistance that storm surge will face.

The second uncertainty involves the resolution of the computational grid, over which the mathematical equations of the surge and wave motion are solved. The resolution determines how well the model sees changes in landscape elevation and land cover and accounts for them, and at how much granularity the physics of hurricane surge and waves is solved.

AI models can produce detailed predictions faster. For example, engineers and scientists have developed AI models based on deep neural networks that can predict water levels along the coastline quickly and accurately by using data about the wind field. In some cases, these models have been more accurate than traditional hydrodynamic models.

AI can also develop forecasts for areas with little historic data, or be used to understand extreme conditions that may not have occurred there before.

For these forecasts, physics-based models can be used to generate synthetic data to train the AI on scenarios that might be possible but haven't actually happened. Once an AI model is trained on both the historic and synthetic data, it can quickly generate surge forecasts using details about the wind and atmospheric pressure.

Training the AI on data from hydrodynamic models can also improve its ability to quickly generate inundation risk maps showing which streets or houses are likely to flood in extreme events that may not have a historical precedent but could happen in the future.

The future of AI for hurricane forecasting

AI is already being used in operational storm surge forecasts in a limited way, mainly to augment the commonly used physics-based models.

In addition to improving those methods, my team and other researchers have been developing ways to use AI for storm surge prediction using observed data, assessing the damage after hurricanes and processing camera images to deduce flood intensity. That can fill a critical gap in the data needed for validating storm surge models at granular levels.

As artificial intelligence models rapidly spread through every aspect of our lives and more data becomes available for training them, the technology offers potential to improve hurricane and storm surge forecasting in the future, giving coastal communities faster and more detailed warnings about the risks on the way.

Some think it's a no brainer: Scattering microscopic particles of sulfur into Earth's atmosphere would reduce the amount of sunlight that reaches the ground, thereby cooling the planet. Indeed, this cooling might temporarily offset the progressing climate change — but a new study claims this type of intervention is likely to have several more unwanted side effects than previously thought.

The concept of geoengineering, or human-induced alteration of the planet's climate, by stratospheric sulfur injections (SAI) is backed by nature's own phenomena. The 1991 eruption of the Philippine stratovolcano Mount Pinatubo injected nearly 20 million tons of sulfur dioxide in the stratosphere, the layer of Earth's atmosphere between altitudes of 7.6 and 31 miles (12 and 50 kilometers). The presence of the sulfur particles in the atmosphere led to a global mean temperature drop of about 1 degree Fahrenheit (0.5 degree Celsius), according to the U.S. Geological Survey.

But that cooling, measurable for two years after the eruption, also disrupted the Indian monsoon system, causing a drought across South Asia, according to the new research paper. Plus, although the sulfur aerosol cooled Earth's surface, it warmed the stratosphere, speeding up ozone destruction.

"There are a range of things that might happen if you try to do this — and we're arguing that the range of possible outcomes is a lot wider than anybody has appreciated until now," Faye McNeill, an atmospheric chemist and aerosol scientist at Columbia’s Climate School and Columbia Engineering and one of the authors of the paper said in a statement.

Researchers are using sophisticated computer models to understand the effects of geoengineering interventions. But McNeill and her colleagues warn that no simulation is perfect and that, in the real world, surprises would be inevitable.

"Even when simulations of SAI in climate models are sophisticated, they're necessarily going to be idealized," McNeill said. "Researchers model the perfect particles that are the perfect size. And in the simulation, they put exactly how much of them they want, where they want them. But when you start to consider where we actually are, compared to that idealized situation, it reveals a lot of the uncertainty in those predictions."

For example, if the geoengineering particles accumulate around the equator, they risk disrupting global atmospheric circulation patterns and alter how heat is distributed around the planet. On the other hand, an accumulation of those particles around the poles could throw out of whack the tropical monsoon system, the researchers explain.

"It isn't just a matter of getting five teragrams of sulfur into the atmosphere. It matters where and when you do it," McNeill said.

On top of that, as the sulfur particles descend toward Earth by the pull of the planet's gravity, they are likely to react with rainwater, forming acidic rain, which in turn harms the soil.

The researchers also looked at alternatives to sulfur but found problems with each of the studied chemical compounds.

"Scientists have discussed the use of aerosol candidates with little consideration of how practical limitations might limit your ability to actually inject massive amounts of them yearly," Miranda Hack, an aerosol scientist at Columbia University and the study’s lead author said in the statement. "A lot of the materials that have been proposed are not particularly abundant."

For example, diamond, cubic zirconia and rutile titania are too rare and too expensive. Other alternatives, including calcium carbonate and alpha aluminum, are plentiful but more difficult to evenly disperse in the atmosphere due to their tendency to create clumps. As a result, these chemicals are not likely to be as effective as sulfur, the researchers said.

The study was published on Oct. 21 in the journal Scientific Reports.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

A clever mathematical tool known as virtual particles unlocks the strange and mysterious inner workings of subatomic particles. What happens to these particles within atoms would stay unexplained without this tool. The calculations using virtual particles predict the bizarre behavior of subatomic particles with such uncanny accuracy that some scientists think "they must really exist."

Virtual particles are not real – it says so right in their name – but if you want to understand how real particles interact with each other, they are unavoidable. They are essential tools to describe three of the forces found in nature: electromagnetism, and the strong and weak nuclear forces.

Real particles are lumps of energy that can be "seen" or detected by appropriate instruments; this feature is what makes them observable, or real. Virtual particles, on the other hand, are a sophisticated mathematical tool and cannot be seen. Physicist Richard Feynman invented them to describe the interactions between real particles.

But many physicists are not convinced by this cut-and-dried distinction. Although researchers can't detect these virtual particles, as tools of calculation they predict many subtle effects that ultrasensitive experiments have confirmed to a mind-boggling 12 decimal places. That precision is like measuring the distance between the North and South poles to better than the width of a single hair.

This level of agreement between measurements and calculations makes virtual particles the most thoroughly vetted idea in science. It forces some physicists to ask: Can a mathematical tool become real?

A bookkeeping tool

Virtual particles are the tool that physicists use to calculate how forces work in the microscopic subatomic world. The forces are real because they can be measured.

But instead of trying to calculate the forces directly, physicists use a bookkeeping system where short-lived virtual particles carry the force. Not only do virtual particles make the calculations more manageable, they also resolve a long-standing problem in physics: How does a force act across empty space?

Virtual particles exploit the natural fuzziness of the subatomic world, where if these ephemeral particles live briefly enough, they can also briefly borrow their energy from empty space. The haziness of the energy balance hides this brief imbalance, which allows the virtual particles to influence the real world.

One big advantage of this tool is that the mathematical operations describing the forces between particles can be visualized as diagrams. They tend to look like stick-figure cartoons of particle pingpong played with virtual particles. The diagrams – dubbed Feynman diagrams – offer an excellent intuitive framework, but they also give virtual particles an aura of reality that is deceiving.

Amazingly, this virtual particle-based method for calculation produces some of the most precise predictions in all of science.

Reality check

All matter is made of basic building blocks called atoms. Atoms, in turn, are made of small positively charged particles called protons found at their core, surrounded by even smaller negatively charged particles called electrons.

As a professor of physics and astronomy at Mississippi State University, I perform experiments that often rely on the idea that the electrons and protons seen in our instruments interact by swapping virtual particles. My colleagues and I have recently measured the size of the proton very precisely, by bombarding hydrogen atoms with a beam of electrons. This measurement assumes that the electrons can "feel" the proton at the center of the hydrogen atom by exchanging virtual photons: particles of electromagnetic energy.

Physicists use virtual particles to calculate how two electrons repel each other, with exquisite precision. The forces involved are represented as the accumulated effect of the two electrons trading virtual photons.

When two metal plates are placed extremely close together in a vacuum, they attract each other: This is known as the Casimir effect. Physicists can accurately calculate the force that pulls the plates together using virtual particle mathematics. Whether the virtual particles are really there or not, the math predicts exactly what researchers observe in the real world.

Yet another mysterious prediction made using the virtual particle tool kit is so-called Hawking radiation. When virtual particle pairs pop into existence at the edge of black holes, sometimes the black hole’s gravity grabs one partner while the other escapes. This rift causes the black hole to slowly evaporate. Although Hawking radiation has not yet been directly observed, researchers have recently observed it indirectly.

Useful fiction

Let's circle back to the question: Can a mathematical tool become real? If you can perfectly predict everything about a force by imagining it is carried by virtual particles, do these particles qualify as real? Does their fictional status matter?

Physicists remain divided on these questions. Some prefer to "just shut up and calculate" – one of Feynman's famous quips. For now, virtual particles are our best way to describe how particles behave. But researchers are developing alternative methods that do not need them at all.

If successful, these approaches could make virtual particles vanish for good. Successful or not, the fact that alternatives exist at all suggests virtual particles might be useful fiction rather than physical truth. It also fits the pattern of previous revolutions in science – the example of ether comes to mind. Physicists invented ether as a medium through which light waves traveled. Experiments matched well with calculations using this tool, yet they could not actually detect it. Eventually, Einstein's theory of relativity showed it was unnecessary.

Virtual particles are a striking paradox of modern physics. They shouldn't exist, yet they are indispensable for calculating everything from the strength of magnets to the behavior of black holes. They represent a profound dilemma: Sometimes the best insights into reality come through carefully constructed illusion. In the end, confusion around virtual particles may be just the price of understanding fundamental forces.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

As Congress faces a Sept. 30, 2025, deadline to fund the federal government, Environmental Protection Agency Administrator Lee Zeldin has put the EPA on the chopping block. But even before Congress decides about the administration's recommendations to slash its staff, the EPA's political leaders have made even more significant cuts to the agency's workforce.

And a look at past efforts to cut EPA staff shows how rapidly those changes can affect Americans' health and the environment.

Using publicly available government databases and a collection of in-depth interviews with current and former EPA employees, the Environmental Data and Governance Initiative, a group of volunteer academics that we are a part of, has begun to put some numbers behind what many have suspected. Zeldin's cuts have diminished the EPA's staffing levels, even before Congress has had a chance to weigh in, affecting the environment, public health and government transparency.

How many people are being let go?

Precise numbers of staffing cuts are hard to pin down, but their historic scale in the first eight months of this administration is unmistakable. Released in May, Zeldin's budget proposal for the fiscal year starting October 2025 proposed to cut 1,274 full-time-equivalent employee positions from a total of 14,130 in the year ending Sept. 30, 2025 – a 9% drop.

A July 18, 2025, press release from the EPA said the agency had already cut 23% of its personnel, terminating the employment of 3,707 of 16,155 employees. Using employees – the number of people – rather than full-time equivalents makes these numbers difficult to compare directly with EPA's budget proposals.

Combining EPA data on staffing changes with conservative estimates of the pending cuts, the initiative has calculated that 25% of EPA staff are already out of the agency.

That calculation does not include other announced cuts, including a third round of deferred resignations taking effect at the end of September 2025 and December 2025. Those cuts may see the departure of similar numbers of full-time equivalents as in the past two rounds – approximately 500 and 1,500.

The agency has also reportedly planned to be cutting as much as two-thirds of research staff.

With those departure figures included, the initiative estimates that approximately 33% of staffers at the agency when Trump took office will be gone by the end of 2025. That would leave, at the start of 2026, an EPA staff numbering approximately 9,700 people, a level not seen since the last years of the Nixon and Ford administrations.

These cuts are deeper than past efforts to shrink the size of the agency. In his first term, Trump proposed eliminating 21.4% of staff at the EPA, though Congress made no significant changes to the agency's staffing. The largest actual cut to EPA staffing was under President Ronald Reagan in the early 1980s: He advocated for a 17.3% drop in staffing, although Congress held the cuts to 10%.

Effects of past cuts

In the past, cuts to the EPA caused problems and were reversed – but it took years.

The staffing and budget cuts that came during the first two years of the Reagan administration generated problems with meeting the agency's responsibilities.

For instance, rather than prosecute industry for polluting, Reagan's EPA Administrator Anne Gorsuch told business leaders she would ignore their violations of environmental laws. Remaining staff were convinced that working on enforcement cases would be a "black mark" on their records.

Another top political appointee at Reagan's EPA, Rita Lavelle, who headed the Superfund effort to clean up toxic sites, faced prison time for her official acts. She was convicted of perjury and obstructing a congressional investigation because she lied about her ties to a former employer who had polluted the Stringfellow Acid Pits, a Superfund site near Riverside, California.

In the wake of the scandal, Lavelle was fired and Gorsuch and more than a dozen other political appointees resigned.

In a later report on the issue, Congress accused Gorsuch, Lavelle and others of poor job performance, noting that after four years of Superfund work, "only six of the 546 … of the most hazardous sites in the Nation have been cleaned up." The Stringfellow site, a focus of the investigation, was "threatening the health and safety of 500,000 people," the report noted.

With anger over the scandals from both Americans and Congress, Reagan reversed course and spent the remaining six years of his presidency building the EPA back up in both staffing and budget. Staffing, for example, increased from a low of 10,481 full-time-equivalent employees in 1982 to 15,130 in 1989. Reagan's EPA budget, which had fallen to US$4.1 billion in 1984, increased to $4.9 billion in 1989.

The existing Trump cuts, and those proposed – if enacted by Congress – would be deeper than Reagan's, reducing the number of people doing important research on environmental harms and the health effects of dangerous chemicals; suing companies who pollute the environment; and overseeing the cleanup of toxic sites.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Back in the 1930s, physicists were doing experiments involving what they called "beta decay." They observed that an element would suddenly spit out a fast-moving electron, and once it was done, it would be different — sometimes a different isotope of the same element, and sometimes a different element altogether.

So the question on everybody's mind was, exactly how did this decay process unfold?

Enrico Fermi had an answer: a new force of nature. We knew that the nucleus of an atom was a bundle of neutrons and protons. Fermi hypothesized that some new force could change a proton into a neutron, or vice versa, and, in the process, release an electron and a nearly massless particle called a neutrino.

It was just a guess. But he was right, and the weak nuclear force was born.

The weak force can do things that no other force can. For example, it can change one flavor of quark into another, which is how neutrons and protons can swap places.

It's also incredibly weak (hence the name). It has a coupling constant, which is a fancy way of describing rare interactions that can happen that are 100,000 times smaller than the electromagnetic force. And it has an incredibly short range. At around 10^-18 meters, it has the same strength as the electromagnetic force, but at just 10^-17 meters, it's over 10,000 times weaker already.

And that incredible weakness comes from another property of the weak force that is totally unlike the other forces, and it has to do with what carries the weak force. All the carriers of all the other forces are massless. But the carriers of the weak force, known as the W and Z bosons, are heavier than a proton.

This was such a big surprise in the 1940s and '50s that it demanded its own explanation. How in the world did the weak force end up with massive force carriers? The answer would come from theoretical physicist Peter Higgs. The whole reason for the existence of the Higgs boson is to explain why the weak force is the way it is, with the side benefit of creating mass for the other particles.

So the weak force doesn't play by the normal rules — and, in fact, it breaks one of the biggest rules of all.

All of the other forces of nature obey something called parity symmetry. If you run a physics experiment and compare it with the same experiment in the mirror, the results should come out the same.

All particles also have a property called helicity, which is their spin relative to their direction of motion. This helicity can be counterclockwise, which we call left-handed, and clockwise, which we call right-handed. All particles spontaneously appear with an even mix of left- and right-handedness. This ensures that their mirror-universe versions are the same, thus maintaining the symmetry of parity.

But neutrinos, which are tiny particles created only by the weak force, do something else. Neutrinos are only ever left-handed. There are no known right-handed neutrinos. If you look at a process involving the weak force in the mirror, you'll see right-handed neutrinos, which don't exist. This breaks the mirror symmetry, and the weak force is the only force to do it.

So the weak force — the force that nobody asked for — is the only force that can change particle flavors, the only force with massive force carriers, and the only force to violate parity symmetry.

And for all that, what do we get? What has the weak force ever done for us?

Well, if you want to fuse two hydrogen atoms together, you can't just do that, because they repel each other. So you need to do a little dance. You need to change one of the protons into a neutron so they can bind together. This creates a deuteron, which is just a fancy name for a proton and a neutron bound together. Those deuterons then go on to fuse to become helium, and energy is released.

And what converts a proton into a neutron? That's right: the weak nuclear force. So, in addition to changing particle flavors, using massive force carriers and making the universe left-handed, the weak nuclear force allows the sun to shine — not a bad trade-off for such a weird force.

Microbes essential for human health have proven resilient against the extreme forces of space travel, offering hope for maintaining astronaut well-being on future long-duration missions.

Researchers from the Royal Melbourne Institute of Technology (RMIT) University in Australia sent spores of the bacterium Bacillus subtilis — a bacterium known to support the human immune system, gut health and blood circulation — in a 3D-printed microtube holder on a sounding rocket flight to test how they would fare under the stresses of launch, microgravity and reentry. Bacteria like B. subtilis will be vital for sustaining human life over decades — a necessity for establishing a presence beyond Earth, such as a future Mars colony.

The microbes were exposed to accelerations of up to 13 times Earth's gravity, a six-minute weightless period at around 162 miles (260 kilometers) altitude, and punishing decelerations reaching 30 g while spinning about 220 times per second during descent. After recovery, scientists found the structure of the spores showed no signs of damage and grew just as they would have on Earth, according to a statement from the university.

"Our research showed an important type of bacteria for our health can withstand rapid gravity changes, acceleration and deacceleration," Elena Ivanova, co-author of the study and professor from RMIT University, said in the statement. "It's broadened our understanding on the effects of long-term spaceflight on microorganisms that live in our bodies and keep us healthy. This means we can design better life support systems for astronauts to keep them healthy during long missions."

Astronauts rely on a healthy microbiome to help regulate digestion, immunity and overall well-being, especially during extended missions. Knowing that beneficial bacteria can survive the harsh transition phases of spaceflight suggests they could be carried safely on journeys to the moon, Mars and beyond.

This marks the first study to test how bacteria respond to the real conditions of spaceflight outside the lab, with findings that could help develop reliable and sustainable life support systems for waste recycling, food production and plant growth during future long-term space missions.

Microbes have previously been studied on the International Space Station (ISS), where spores have endured months in the airless vacuum of space and exposed to harsh radiation. What sets this experiment apart is its focus on the real stresses of a rocket flight from launch to landing. While B. subtilis spores are exceptionally hardy, the study offers a benchmark for testing other microbes more directly tied to human health and agriculture, the researchers said.

Understanding microbial resilience in harsh environments also has benefits on Earth, by helping scientists develop new antibacterial treatments and strategies to fight antibiotic-resistant bacteria, while offering fresh clues for the search for life on other planets.

"It could guide the development of more effective life-detection missions, helping us to identify and study microbial life forms that could thrive in environments previously thought to be uninhabitable," Ivanova said in the statement.

Their findings were published Oct. 6 in the journal npj Microgravity.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

As I walked out onto the frozen Arctic water off Utqiagvik, Alaska, for the first time, I was mesmerized by the icescape.

Piles of blue and white sea-ice rubble several feet high gave way to flat areas and then rubble again. The snow atop it, sometimes several feet deep, hides gaps among the blocks of sea ice, as I found out when one of my legs suddenly disappeared through the snow.

As a polar climate scientist, I have focused on Arctic sea ice for over a decade. But spending time on the ice with people who rely on it for their way of life provides a different perspective.

Local hunters run snowmobiles over the sea ice to reach the whales and seals they rely on for traditional food. They talked about how they know when the sea ice is safe to travel on, and how that's changing as global temperatures rise. They described worsening coastal erosion as the protective ice disappears earlier and forms later. On land, they're contending with thawing permafrost that causes roads and buildings to sink.

Their experiences echo the data I have been working with from satellites and climate models.

Most winters, sea ice covers the entire surface of the Arctic Ocean basin, even extending into the northern North Atlantic and North Pacific. Even in late summer, sea ice used to cover about half the Arctic Ocean. However, the late summer ice has declined by about 50% since routine satellite observations began in 1978.

This decline of summer sea ice area has a multitude of effects, from changing local ecosystems to allowing more shipping through the Arctic Ocean. It also enhances global warming, because the loss of the reflective white sea-ice surface leaves dark open water that absorbs the sun's radiation, adding more heat to the system.

What coastal communities are losing

Along the Alaskan coast, the decline of the Arctic sea ice cover is most apparent in the longer ice-free season. Sea ice is forming later in the fall now than it used to and breaking up earlier in the spring.

For people who live there, this means shorter seasons when the ice is safe to travel over, and less time when sea ice is present to protect the coastline from ocean waves.

Open water increases the risk of coastal erosion, particularly when accompanied by thawing permafrost, stronger storms and rising sea level. All are driven by greenhouse gas emissions from human activities, particularly burning fossil fuels.

In some places along the Alaskan coast, erosion threatens roads, houses and entire communities. Research has shown that coastal erosion in Alaska has accelerated over recent decades.

More weeks of open water also affect animals. Polar bears spend the summer on land but require sea ice to hunt their preferred food, seals. The longer the sea ice stays away from land, the longer polar bears are deprived of this high-fat food, which can ultimately threaten the bears' survival.

The ice is also thinning and getting younger

Across the Arctic, satellite data has captured how sea ice has been thinning and getting younger.

As recently as the late 1970s, about 60% of the Arctic sea ice was at least 1 year old and generally thicker than younger ice. Today, the amount of ice more than a year old is down to about 35%.

Local residents experience that change in another way: Multiyear sea ice is much less salty than new sea ice. Hunters used to cut blocks of multiyear sea ice to get drinking water, but that older ice has become harder to find.

Sea ice forms from ocean water, which is salty. As the water freezes, the salt collects in between the ice crystals. Because the higher the salt content, the lower the freezing point of the water, these enclosures in the sea ice contain salty liquid water, called brine. This brine drains out of the sea ice over time through small channels in the ice. Thus, multiyear sea ice, which has survived at least one melt cycle, is less salty than first-year sea ice.

Since the coastal landfast sea ice around Utqiagvik no longer contains much multiyear sea ice, if any, the hunters now have to take a block of lake ice or simply gallon jugs of water with them if they plan to stay on the ice for several days.

Why data shows a continuing decline

As long as greenhouse gas emissions continue to increase, Arctic sea ice will generally continue to decline, studies show. One study calculated that, statistically, the average carbon dioxide emissions per person per year in the U.S. led to the disappearance of an area of summer sea ice the size of a large hotel room – 430 to 538 square feet (40 to 50 square meters) each year.

Today, when Arctic sea ice is at its minimum extent, at the end of summer, it covers only about half what it covered in 1979 at that time of the year. The Arctic still has around 1.8 million square miles (4.6 million square kilometers) of sea ice that survives the summer melt, approximately equal to the area of the entire European Union.

Climate models show the Arctic could be ice-free at the end of summer within decades, depending on how quickly humans rein in greenhouse gas emissions.

While a win for accessibility of shipping routes through the Arctic in summer, studies suggest that the large reduction of sea ice would bring profound ecological changes in the Arctic Ocean, as more light and heat enter the ocean surface.

The warmer the surface ocean water is, the longer it will take for the ocean to cool back down to the freezing point in the fall, delaying the formation of new sea ice.

What now?

Arctic sea ice will continue to form in winter for the next several decades. The months of no sunlight mean it will continue to get very cold in winter, allowing sea ice to form.

Climate models have estimated that it would take extremely high atmospheric carbon dioxide concentrations to warm the climate enough for no sea ice to form in the winter in the Arctic Ocean – close to 2,000 parts per million, more than 4.5 times our current level.

However, winter sea ice will cover less area as the Earth warms. For people living along the Arctic Ocean coast in Alaska, winter ice will still return for now. If global greenhouse gas emissions are not reduced, though, climate models show that even winter sea ice along the Alaskan coast could disappear by the end of the 21st century.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

From a distance, Biosphere 2 emerges from the cacti and creosote of the Sonoran desert like a gleaming oasis, a colony of glass and bright white structures. Despite being just outside Tucson, Arizona, it looks almost like a colony on another planet.

When one of the facility's 100,000 annual visitors steps inside, they see a whole world – from a tropical rainforest, glistening in 50 shades of green and teeming with life, to a miniature, experimental ocean. Toward the end of the tour, the visitor comes to a comparatively barren-looking experiment called the Landscape Evolution Observatory, where life is struggling to establish itself on crushed volcanic rock originally spewed from an ancient Arizonan volcano.

It is these rock slopes, where life is colonizing and transforming a tough landscape, that our team thinks are the key to humanity’s future – both on Earth and, eventually, on other worlds.

Biosphere 2 first became famous as the human experiment of the 1990s that sealed a group of eight researchers inside its 3 acres of diverse ecosystems for two long years. The goal was to experiment with the viability of a closed ecological system to maintain human life in outer space. Today, we – a global change ecologist, an astronomer and a doctoral student specializing in microbial biogeochemistry, along with our team of colleagues – have made Biosphere 2 into a test bed for understanding how life transforms landscapes, from local areas to whole planets.

We hope to use what we learn to help preserve biodiversity, access to fresh water and food security. To address these issues, we must understand how soil, rocks, water and microbes together drive the transformation of landscapes, from local to planetary scales.

Beyond Earth, these same principles apply to the challenge of terraformation: the science of rendering other worlds habitable.

How life on Earth affects the Earth

Life doesn't just sit on the Earth's surface. Organisms profoundly affect the planet's geology, as well as the atmosphere's composition. Biology can transform barren environments into habitable ecosystems.

This happened with the evolution of cyanobacteria, the first microscopic organisms to use oxygen-producing photosynthesis. Cyanobacteria pumped oxygen into the atmosphere 2 billion to 3 billion years ago.

Atmospheric oxygen, in turn, enabled a new supercharged metabolism of life called aerobic, or oxygen-using, respiration. Aerobic respiration produced so much energy that it became the dominant way for organisms to make the energy needed for life, eventually making multicellular life possible.

In addition, the oxygen produced by photosynthesizing cyanobacteria also made its way to the upper atmosphere, forming another kind of oxygen known as ozone, which, by shielding the Earth's surface from sterilizing ultraviolet radiation, allowed life to expand onto land.

Biology again transformed the planet when the life that expanded onto land 400 million years ago gave a biological boost to the chemical and geological process known as weathering. Weathering occurs when carbon dioxide in the atmosphere chemically reacts with material on Earth's surface – such as rocks, minerals and water – to create soils imbued with nutrients that can support plants and other living organisms.

On Earth, weathering was first driven by purely physical and chemical processes. Once plants expanded from the oceans onto land, however, their roots injected carbon dioxide directly into the soil where weathering reactions were strongest. This process sucked carbon dioxide out of the atmosphere. Lower carbon dioxide levels in the atmosphere then cooled the Earth, turning a hothouse planet into one with a more temperate climate, like the one enjoyed by life today.

How organisms colonize new landscapes

When life colonizes a new, previously barren landscape, it starts up the process of primary succession. In this process, the first biological organisms – simple microbes – expand into interacting communities made of different kinds of organisms, which increase in complexity and biodiversity as they change and adapt to fit their new environment.

These microbes react with the air and rock through photosynthesis and respiration to produce organic molecules called metabolites. The metabolites can alter the soil, allowing it to support larger plants. The larger plants that then emerge have complex structures such as roots and leaves that regulate the flow of water – and contribute to weathering. Eventually, humans can domesticate some of these plants for food crops.

Biosphere 2's Landscape Evolution Observatory is ideal for the careful study of how weathering and primary succession work together. Those processes both happen at the small, molecular scale but emerge as important only over large areas.

The Landscape Evolution Observatory has both hillslopes larger than any experiment in the world and crushed rock soils that are more simple and uniform than almost any natural setting. These characteristics mean the molecular measurements are consistent and understandable, even in different places across the larger hillslope.

The observatory is made up of three hillslopes covering 300 square yards that look like three giant tray-shaped, inclined planters made of steel, filled with crushed rock instead of fertile soil. The rain that falls on them soaks into the surface and flows down the incline to dribble out along the lower edge, where it is captured and carefully measured for its chemical and biological content.

We are using biological tools to understand how microbes and simple plants end up spreading across the larger, originally bare, crushed-rock hillslopes. These techniques include metagenomics, which can identify all the microbial life forms in a hillslope, and metabolomics, which can look at the organic molecules that microbes and plants produce and use in their interactions with each other and their surroundings.

Putting this all together, we see that colonies of photosynthesizing bacteria initiate succession on the Landscape Evolution Observatory. Critically, these cyanobacteria – descendants of those same organisms that gave Earth oxygen – capture the essential nutrient, nitrogen, from the air. Nitrogen buildup paves the way for mosses – simple plants without roots – to join them.

These bacteria-moss communities are now gradually spreading across the observatory's hillslopes, preparing the way for the next phase: colonization by larger plants with roots.

By learning how life establishes itself and then thrives on lifeless landscapes, we will gain insights for addressing key problems scientists face today. For example, when life-forms in a new landscape successfully spread and diversify, they tell us how biodiversity is preserved.

When those spreading organisms transform the way a landscape uses water, they give us lessons on how we should use water. And when plants find a way to be productive under stressful conditions, they give us examples for increasing our own plant-dependent food security.

Implications for Mars

Earth isn't the only planet where we can apply our findings. Today, Mars, unlike Earth, is a barren, lifeless desert. But it was once warmer, wetter and, like the early Earth, it may have hosted primitive living organisms several billion years ago.

While the rock in the Landscape Evolution Observatory comes from an Arizona volcano, basalt is the same kind of rock found on the surface of the Moon and Mars.

Countries such as the United States and China plan to land humans on Mars, and the company SpaceX has grandiose plans to send a million colonists there. If humans ever hope to grow plants on the red planet’s surface, learning how to create early succession there will prove crucial.

Before Mars colonization can happen at a large, sustainable scale, the first step is to grow plants and create food for human life. That is, we must solve what might be called the "Matt Damon problem," after the actor in the movie "The Martian." In order to survive, his character had to quickly learn to grow food crops – potatoes – on Mars.

Matt Damon's character would probably not have survived on the real Mars of today, because its rocklike surface, called regolith, is too full of salts and toxic chemicals such as perchlorate for potatoes, or most Earth-like plants, to grow.

At the Landscape Evolution Observatory, we are focusing on experiments in chambers that simulate Martian environments to ask what it will take to detoxify Mars-like soils so that microbes and plants can live there.

One initial approach is to use perchlorate-reducing bacteria, recruited from extreme environments on Earth, to convert the perchlorate into harmless chloride.

In this way, experiments at Biosphere 2 are informing the science of terraforming Mars. Together with progress made in other areas, such as finding ways of making Mars warm enough to sustain liquid water, restoring barren environments on Earth could be a key to one day living on Mars.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

There are a record number of conflicts raging around the world – from Ukraine and Gaza to Sudan and Myanmar. Alongside their devastating human toll, these conflicts are all wreaking havoc on the environment.

One of the key ways war leads to environmental harm is by leaving behind unexploded weaponry. Since the start of Russia's full-scale invasion in 2022, Ukraine has become the most landmine-contaminated country in the world. By January 2024, roughly 25,000 sq km of agricultural land there was estimated to have been contaminated with landmines and other so-called explosive remnants of war.

The contamination of Ukrainian farmland – alongside the physical damage from exploded mines – has contributed to a sharp decrease in agricultural activity, with wheat production in Ukraine falling by 41% between 2021 and the end of 2024. Ukraine has historically been one of the world's largest agricultural exporters.

The damage wars are causing to land is also occurring at a time when climate change is driving land degradation. Rising temperatures, increased aridity and the intensification of extreme weather events are leading to reduced soil fertility and desertification. This often compounds the impact of unexploded mines and bombs on the land.

The human toll from explosive remnants of war is quite visible, as the number of deaths resulting from unexploded mines and bombs can be traced. In April 2024, for example, the Ukrainian government reported that landmines and other unexploded ordnance had accounted for more than 1,000 civilian casualties since the start of Russia's invasion.

But the impact of explosive remnants on the land is less immediately apparent. Research in Cambodia, which was bombed extensively by the US military during the Vietnam war (1955-1975), suggests that unexploded ordnance continues to harm agricultural productivity there today.

Many of the bombs that landed on soft and highly fertile land failed to detonate. They continue to render the land hazardous. Due to the danger of unexploded bombs, many Cambodian farmers avoid using tractors and other agricultural techniques that could increase agricultural production.

Studies also show that explosive remnants of war affect soil quality. Unexploded bombs and landmines can leak heavy metals and toxic waste into the soil, polluting land and water. In rare cases, contaminants from a landmine have been detected up to 6km away from the initial explosion site.

The methods for clearing unexploded ordnance can contribute to land degradation, too. Heavy demining equipment can damage fertile top soil and contribute to erosion. Some methods of disposal, such as controlled detonations, can also release contaminants into the soil.

Research on soil quality in the Halgurd-Sakran National Park in north-eastern Iraq, a region that has seen decades of armed conflict, show evidence of the release of hazardous metals such as lead, cadmium and arsenic into the soil following demining activities.

These contaminants pose significant risks both to local ecosystems and human health through direct contact and the contamination of water sources and food chains. There are also risks of contamination through inhaling or ingesting dust.

Climate change complications

Climate hazards such as droughts, floods and wildfires can exacerbate the impact of explosive remnants of war. Floods and heavy rainfall can unearth landmines and other unexploded ordnance, sometimes displacing them into areas previously considered safe.

High temperatures from heatwaves can also cause abandoned munitions to explode. Six different munition sites exploded across Iraq during scorching hot summers in 2018 and 2019, when temperatures regularly topped 45°C. Heatwaves were blamed for a similar arms dump explosion in Jordan in 2020.

At the same time, the presence of explosive remnants in the environment can hamper responses to climate events. In eastern Ukraine, for example, the heavy contamination of forests with landmines and tripwires prevented fire crews from responding effectively to wildfires in 2020. The fires damaged houses and killed seven people.

Similarly, unexploded bombs from the second world war have been detonated recently by wildfires in the North York Moors, UK. This increases the unpredictability of the fires, inevitably endangering the the lives of fire crews.

In Libya, Storm Daniel destroyed two dams in 2023 and subsequently caused flooding in large parts of the eastern city of Derna. The displacement of unexploded ordnance and ammunition stores caused by the flooding complicated recovery efforts.

Explosives experts also had to be deployed during the destructive floods in South Sudan in 2024 to assess whether land was safe for the relocation of displaced people.

Climate disasters and environmental change can also prevent communities from benefiting from land that has been cleared of explosive remnants after the end of war.

In Angola, where there was a civil war between 1975 and 2002, drought has prevented farmers from planting crops in recently cleared fields. Increasing soil salinisation in Sri Lanka due to rising sea-levels has also affected the ability of farmers to plant rice in areas cleared of unexploded munitions.

Explosive remnants of war have a lasting impact, not only on human life but also the environment. Climate change is only making the threat more unpredictable and challenging to address.

It's more important than ever that measures to restore land, tackle climate change and manage the impact of armed conflict – including explosive remnants of war – are addressed together rather than in isolation.

This article is republished from The Conversation under a Creative Commons license. Read the original article

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

For farmers, every planting decision carries risks, and many of those risks are increasing with climate change. One of the most consequential is weather, which can damage crop yields and livelihoods. A delayed monsoon, for example, can force a rice farmer in South Asia to replant or switch crops altogether, losing both time and income.

Access to reliable, timely weather forecasts can help farmers prepare for the weeks ahead, find the best time to plant or determine how much fertilizer will be needed, resulting in better crop yields and lower costs.

Yet, in many low- and middle-income countries, accurate weather forecasts remain out of reach, limited by the high technology costs and infrastructure demands of traditional forecasting models.

A new wave of AI-powered weather forecasting models has the potential to change that.

By using artificial intelligence, these models can deliver accurate, localized predictions at a fraction of the computational cost of conventional physics-based models. This makes it possible for national meteorological agencies in developing countries to provide farmers with the timely, localized information about changing rainfall patterns that the farmers need.

The challenge is getting this technology where it's needed.

Why AI forecasting matters now

The physics-based weather prediction models used by major meteorological centers around the world are powerful but costly. They simulate atmospheric physics to forecast weather conditions ahead, but they require expensive computing infrastructure. The cost puts them out of reach for most developing countries.

Moreover, these models have mainly been developed by and optimized for northern countries. They tend to focus on temperate, high-income regions and pay less attention to the tropics, where many low- and middle-income countries are located.

A major shift in weather models began in 2022 as industry and university researchers developed deep learning models that could generate accurate short- and medium-range forecasts for locations around the globe up to two weeks ahead.

These models worked at speeds several orders of magnitude faster than physics-based models, and they could run on laptops instead of supercomputers. Newer models, such as Pangu-Weather and GraphCast, have matched or even outperformed leading physics-based systems for some predictions, such as temperature.

AI-driven models require dramatically less computing power than the traditional systems.

While physics-based systems may need thousands of CPU hours to run a single forecast cycle, modern AI models can do so using a single GPU in minutes once the model has been trained. This is because the intensive part of the AI model training, which learns relationships in the climate from data, can use those learned relationships to produce a forecast without further extensive computation – that's a major shortcut. In contrast, the physics-based models need to calculate the physics for each variable in each place and time for every forecast produced.

While training these models from physics-based model data does require significant upfront investment, once the AI is trained, the model can generate large ensemble forecasts — sets of multiple forecast runs — at a fraction of the computational cost of physics-based models.

Even the expensive step of training an AI weather model shows considerable computational savings. One study found the early model FourCastNet could be trained in about an hour on a supercomputer. That made its time to presenting a forecast thousands of times faster than state-of-the-art, physics-based models.

The result of all these advances: high-resolution forecasts globally within seconds on a single laptop or desktop computer.

Research is also rapidly advancing to expand the use of AI for forecasts weeks to months ahead, which helps farmers in making planting choices. AI models are already being tested for improving extreme weather prediction, such as for extratropical cyclones and abnormal rainfall.

Tailoring forecasts for real-world decisions

While AI weather models offer impressive technical capabilities, they are not plug-and-play solutions. Their impact depends on how well they are calibrated to local weather, benchmarked against real-world agricultural conditions, and aligned with the actual decisions farmers need to make, such as what and when to plant, or when drought is likely.

To unlock its full potential, AI forecasting must be connected to the people whose decisions it’s meant to guide.

That's why groups such as AIM for Scale, a collaboration we work with as researchers in public policy and sustainability, are helping governments to develop AI tools that meet real-world needs, including training users and tailoring forecasts to farmers' needs. International development institutions and the World Meteorological Organization are also working to expand access to AI forecasting models in low- and middle-income countries.

AI forecasts can be tailored to context-specific agricultural needs, such as identifying optimal planting windows, predicting dry spells or planning pest management. Disseminating those forecasts through text messages, radio, extension agents or mobile apps can then help reach farmers who can benefit. This is especially true when the messages themselves are constantly tested and improved to ensure they meet the farmers’ needs.

A recent study in India found that when farmers there received more accurate monsoon forecasts, they made more informed decisions about what and how much to plant – or whether to plant at all – resulting in better investment outcomes and reduced risk.

A new era in climate adaptation

AI weather forecasting has reached a pivotal moment. Tools that were experimental just five years ago are now being integrated into government weather forecasting systems. But technology alone won't change lives.

With support, low- and middle-income countries can build the capacity to generate, evaluate and act on their own forecasts, providing valuable information to farmers that has long been missing in weather services.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

The western United States is facing another destructive wildfire season, with more acres burned in Colorado alone in 2025 than in the past four years combined. If global warming continues on its current trajectory, the amount of forest area burned each year could double or even triple by midcentury.

In other words, more fire is coming, more often.

As U.S. forests burn, Congress and federal agencies are asking an important question: What role should federal land management play in reducing fire risk?

About two-thirds of forest land in the western U.S. is publicly owned, with the majority of it managed by federal agencies such as the U.S. Forest Service and Bureau of Land Management. These public lands are treasured for recreation, wildlife habitat, timber production and open space. They are also where many of today's largest fires burn.

Historically, lightning- and human-ignited fires kept forests less dense and reduced forest litter and undergrowth that can easily burn. While some controlled burning continues today, the violent displacement of Native people, criminalization of Indigenous fire stewardship and more than a century of federal fire suppression have largely removed fire as a critical ecological process in fire-prone forests, leaving fuel to accumulate.

When those forests burn today, the result is often hotter and more severe fires that elude any attempt at control. And rising global temperatures are raising the risk.

Several of the current federal proposals for managing fire risk focus on increasing timber harvesting on federal lands as a solution. They also propose speeding up approvals for those projects by limiting environmental reviews and public oversight.

As experts in fire science and policy, we see some useful ideas in the proposed solutions, but also reasons for concern.

While cutting trees can help reduce the severity of future fires, it has to include thinning in the right places to make a difference. Without oversight and public involvement, increasing logging could skip areas with low-value trees that need thinning and miss opportunities for more effective fire risk-reduction work.

Harvesting timber to reduce fire risk

President Donald Trump cited wildfire risk in his March 2025 executive order calling for "an immediate expansion of American timber production." And the U.S. Forest Service followed with a commitment to increase timber sales on federal land by 25% over the next four years.

Trump, federal officials and members of Congress who are advancing legislation such as the Fix Our Forests Act have also called for speeding up approval of timber-harvesting projects by reducing public comment periods on proposals, limiting environmental analyses of the plans and curtailing the ability of groups to sue to block or change the projects in court.

These proposals are often framed as pragmatic solutions to clear the way for action to reduce fire risk faster. The urgency is real, and this argument can seem intuitive. No one wants burdensome processes to stand in the way of reducing wildfire damage. But it’s important to take a hard look at the problem and real solutions.

Environmental reviews aren't the problem

Research shows that environmental reviews are rarely the main barrier to forest projects aimed at reducing fire risk.

The bigger obstacles are the shrinking of the federal forest workforce over the past two decades, the low commercial value of the small trees and brush that need to be removed, and the lack of contractors, processing facilities and markets for low-value wood.

Data from the U.S. Forest Service supports these conclusions.

Between 2005 and 2018, over 82% of the U.S. Forest Service's land management projects were approved using categorical exclusions. Categorical exclusions allow agencies to skip environmental assessments and are the fastest and least burdensome form of National Environmental Policy Act, or NEPA, review, with limited analysis or opportunity for public involvement.

Less than 1% of the projects were challenged in court, and most of those challenges targeted the largest and most complex projects, where public oversight and analysis are critical to getting it right on the ground, such as large mining operations or forest management projects that would cover hundreds of thousands of acres.

An analysis of the bulk of U.S. Forest Service land management projects between 2009 and 2021 found that complying with NEPA took between 7% and 21% of the projects' timelines, often shorter than the timelines for issuing contracts.

Some degree of planning, intergovernmental coordination and public involvement must happen before starting a fuel-reduction project to know where the work is appropriate and necessary.

Why reviews and public oversight matter

What would be lost if environmental-analysis and public-involvement requirements were curtailed?

Oversight helps ensure that projects happen where they are needed to reduce fire risk. Without that, political and economic pressures can lead to more forest thinning in locations where there are mills and valuable timber – rather than in the areas where wildfire risk is higher but the trees aren't as valuable.

Environmental review and public comment are among the few tools communities have to shape fire-mitigation projects.

These processes also ensure that the work doesn't stop at federal boundaries. And they help partners, such as community organizations, state agencies and local fire departments, plan and work together.

Oversight doesn't just protect the environment — it enables funding and partnerships, safeguards communities and builds shared ownership of adapting to fire.

Solutions that work

So, what can Congress and the federal government do to reduce fire risk to communities? The answer starts with investing in forest management and projects that can reduce fire risk.

Joint projects involving communities and state, tribal and local agencies, like those under the Collaborative Forest Landscape Restoration Program, build partnerships to reduce fire risk across large landscapes and lower the risk of fire spreading to homes and federal wildlands. The Good Neighbor Authority, created in 2001, enables federal agencies to contract with states, counties and tribes to provide forest management work on federal lands.

Yet federal funding for state, tribal and private forest management is on the chopping block. Wildfire risk and the capacity to address the challenge are going in opposite directions.

The Wildland Fire Mitigation and Management Commission, a bipartisan group of fire professionals, scientists, tribes, land managers and local officials, recently released recommendations for improving fire management that call for greater funding and collaboration at all levels to reduce the fire risk. The report emphasizes the importance of proactive solutions driven by local communities, shared decision-making and better use of prescribed fire. Achieving these goals will require sustained collaboration across jurisdictions and sectors, with communities engaged as full partners in the process.

Forest and fire management are complex jobs. It is reasonable to yearn for quick solutions to the wildfire crisis, but it's important that any fixes lead to lasting progress. Deregulation and disinvestment may ultimately exacerbate wildfire risk.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Particle accelerators, also known as particle colliders or atom smashers, have been responsible for some of the most exciting physics findings over the past century, including the discovery of the elusive Higgs boson, the fundamental force-carrying particle of the Higgs field, which gives other particles their mass.

But how do particle colliders work?

As the name suggests, particle accelerators involve accelerating subatomic particles to incredibly high speeds and smashing them into tiny targets, usually atomic nuclei, to achieve a desired effect.

To get an idea of the scales at which particle accelerators work, consider one of the basic units used in their applications: the "barn." It's equal to a square just 10 femtometers — 10 quadrillionths of a meter — on each side. And yes, the term, coined in the 1940s by physicists at Purdue University in the heart of the Midwest, is meant to invoke such sayings as "That's as big as a barn" and "You couldn't hit the broad side of a barn."

However, the simplest and earliest accelerators were relatively straightforward devices. There was a source of electrons, and then you launched those electrons through a cavity filled with electric fields. The electrons hit something on the other side of the cavity. Done.

For a few decades, most people in the U.S. had such a particle collider in their home: a CRT television. CRT stands for "cathode ray tube," and cathode rays are an old name for electrons (before scientists realized that electrons are particles). The electrons accelerated and smashed into a phosphorescent screen that lit up for our viewing pleasure.

Naturally, these kinds of colliders have limits on the size of the cavity and the strength of the electric field you can put in that cavity. So the next step in the evolution of colliders was known as a linear collider. The largest one operating today is the SLAC National Accelerator Laboratory, a 2-mile-long (3.2 kilometers) device outside San Francisco.

The idea behind a linear collider is to repeat the basic operation of simpler colliders. Most importantly, electric fields can either push or pull on electric charges, depending on their direction. So, as a charged particle enters a chamber, the electric field pulls on it to accelerate it. Then, once it gets halfway through, the electric field switches into "push" mode, which continues the acceleration.

Next, the charge exits that cavity and enters another with the same setup — and then another, and then another, repeated as long as you can get away with it (or until funding runs out).

Small linear accelerators power a variety of applications around the world. Need an X-ray at the dentist? There's an accelerator that fires electrons at a piece of metal to generate those X-rays. Need a tumor removed? A proton accelerator makes a great device for targeting cancer cells without harming surrounding tissue. Need a new semiconductor? An ion implanter paints microscopic transistors to create circuits. Need new tires? An accelerator has cross-linked those polymers to make the plastics and synthetic rubber more durable.

But what if you could keep the charge accelerating for an infinite length? The easiest way to make a finite line infinite is to bend it into a circle. The charge can then keep looping around and around, without reaching a stopping point.

But one of the main challenges with this is a bottleneck from relativity. As the particle speeds up, it gains kinetic energy — and energy equals mass, so effectively, the particle gets heavier and heavier. This isn't so much from a pure acceleration standpoint; it's kind of easy to just keep pushing subatomic particles harder. Rather, to keep them moving in a circle, we need to employ magnetic fields. At a heavier mass, the magnetic field can't keep up, and the particle starts to drift and slam into the side of the circular chamber.

So the magnetic field has to stay synchronized with the increasing mass of the particle, ramping up in strength as the particle whips around. Thus, we call these kinds of accelerators synchrotrons.

The flagship synchrotron is the Large Hadron Collider (LHC), operated by CERN (the European Organization for Nuclear Research). It features a ring with a circumference of 16.8 miles (27 km) holding 36,000 tons of magnets and chilled to minus 459.58 degrees Fahrenheit (minus 273.1 degrees Celsius) — colder than outer space — and it can accelerate protons to 99.9997828% the speed of light.

The LHC works in both directions at once. Then, at the last minute — right when the two particle beams have reached their peak energy — they slam into each other head-on at a total energy of 14 tera electron volts.

That's less than a billionth of the energy of a thrown baseball. But considering all that energy is crammed into an incredibly tiny area, the energy densities reach conditions not seen in the universe since the earliest moments of the Big Bang. At those energies, short-lived particles appear from the vacuum, giving physicists a glimpse of the most basic operations of nature.

Astronomers have launched a new program known as ATREIDES to study a mysterious "desert" in space. But unlike the deserts of the planet Arrakis conquered by Paul Atreides in the "Dune" novels by Frank Hebert, this desert describes an absence of planets with masses up to around 20 times the mass of Earth that orbit close to their stars, planets scientists refer to as "hot Neptunes."

The first planets studied by the ATREIDES program, the two worlds of the TOI-421 system, demonstrate misaligned orbits, hinting that this system experienced a more chaotic evolution than our solar system. Studying it could help astronomers figure out why these "hot Neptunes" appear to be so rare in the cosmos, as well as teach us about how planets form elsewhere in the universe.

"The complexity of the exo-Neptunian landscape provides a unique window onto the processes involved in the formation and evolution of planetary systems," ATREIDES Principal Investigator and University of Geneva (UNIGE) researcher Vincent Bourrier said in a statement describing the ATREIDES program.

To understand why this class of extrasolar planet, or "exoplanet," is missing from close orbits around other stars, ATREIDES scientists investigated the TOI-421 planetary system. Located around 244 light-years from Earth, TOI-421 is an orange dwarf or "K-type" star orbited by two exoplanets, TOI-421 b and TOI-421 c. What this investigation revealed is a surprisingly tilted orbital situation in TOI-421 that implies that this system experienced a chaotic history, one which may help explain why hot Neptunes are so rare.

TOI-421 b is a scorching hot sub-Neptune planet with a mass around 7 times that of Earth that orbits its star at a distance equivalent to around 6% of the distance between our planet and the sun. TOI-421 c is larger, with a mass of around 14 times that of Earth, which orbits its star at a distance equivalent to around 12% the distance between Earth and the sun, making it a hot Neptune and putting it in a region adjacent to the Neptunian desert called "the savanna."

"A thorough understanding of the mechanisms that shape the Neptunian desert, savanna, and ridge will provide a better understanding of planetary formation as a whole ... but it's a safe bet that the universe has other surprises in store for us, which will force us to develop new theories," Bourrier said.

Mapping the Neptunian desert

Over the last 10 years of exoplanet observations, the Neptunian desert has become increasingly complex. Areas further out from stars than the Neptunian desert have been found to be more generously populated with Neptune-sized worlds. This more temperate realm with more Neptune-like exoplanets has come to be known as the "savanna" of the Neptunian desert.

Astronomers have also defined a region between the Savanna and the Neptunian desert, which they call the "Neptunian ridge." This region is more densely populated by Neptune-like worlds than both the desert and the savanna. The scientists of the ATREIDES program aim to understand these three distinct regions by identifying the processes that lead to the relative planetary populations.

The team wants to test the hypothesis that the Neptunian landscape is created as a result of the way that planets migrate from their birthplaces to the orbits we observe them in.

Some exiled planets would migrate slowly through the disk of gas and dust that exists in these systems during their infancy. This sedate migration should produce planets in orbits aligned with their star's equator and the orbits of the other planets in their home system. That is similar to the orbits of the planets in the solar system, which are aligned almost to the equatorial plane of the sun.

However, some other planets would be violently thrown from their site of formation via a chaotic process called "high-eccentricity migration." That should result in those planets falling into highly misaligned orbits.

That means the alignment between a star's orbital plane and the orbital plane of its planets is key to investigating this migration hypothesis.

The team can't yet say anything conclusive yet about the Neptunian desert, its neighboring regions, or planetary evolution in general. Many more observations of more planetary systems with hot Neptunes will be needed for that.

However, this research successfully demonstrates the effectiveness of the ATREIDES program and the techniques it has developed and employed.

The team's research was published on Tuesday (Sept. 16) in the journal Astronomy & Astrophysics.

Astronomers have used an X-ray spacecraft called XRISM to observe powerful winds blowing from a neutron star — the findings could be a "game changer" for physics.

The team discovered unexpected differences between powerful and energetic winds blowing from swirling disks of gas and dust, called accretion disks, around extreme "dead stars," or neutron stars, and winds that flow from accretion disks that feed supermassive black holes at the hearts of large galaxies.

The discovery could reveal more about the physics surrounding the inflow of matter from accretion disks to the surfaces of both neutron stars and supermassive black holes, as well as the outflow of winds from these disks. Understanding such dynamics could, in turn, reveal how these winds influence the cosmic surroundings of supermassive black holes.

The team discovered the surprising differences between supermassive black hole and neutron star accretion disks when they used the NASA/JAXA spacecraft XRISM (X-Ray Imaging and Spectroscopy Mission) to observe powerful winds flowing from accretion disk GX13+1, located between 23,000 and 26,000 light-years from Earth in the galactic bulge of the Milky Way.The observing power of XRISM's Resolve instrument allowed the team to measure the energy of X-ray light emitted from GX13+1 and gather details about its system that had never been seen before.

"When we first saw the wealth of details in the data, we felt we were witnessing a game-changing result," European Space Agency (ESA) XRISM project scientist Matteo Guainazzi said in a statement. "For many of us, it was the realization of a dream that we had chased for decades."

Cosmic winds of change

It may seem strange to investigate supermassive black hole winds by studying the wind blowing from a neutron star, but the team behind this research reasoned that the mechanisms behind these different outflows are similar. Also, the closest supermassive black hole to us, the Milky Way's Sagittarius A* (Sgr A*), isn't actively feeding because it isn't surrounded by enough matter to form an accretion disk.

GX13+1 is closer and brighter than the feeding supermassive black holes in other galaxies that could be used for this kind of investigation, allowing it and the physics driving its winds to be studied in greater detail.

However, before the observations of GX13+1 could even begin, this neutron star delivered a surprise to the team, brightening so much the researchers theorized it may have reached or even exceeded the Eddington limit.

This theoretical limit concerns how much matter can be accreted to a compact body like a neutron star or black hole. The more matter accreted, the more energy emitted and thus the more outward pressure exerted on infalling material. When the Eddington limit is reached, the outward pressure of this energy is so great that the supply of material to the compact celestial body is cut off, and the surrounding material is pushed away as cosmic winds.

Via Resolve, the team watched as GX13+1 hit this ceiling.

"We could not have scheduled this if we had tried," team leader Chris Done from Durham University in the UK, said. "The system went from about half its maximum radiation output to something much more intense, creating a wind that was thicker than we'd ever seen before."

However, this wasn't the end of the surprises delivered by this wind. It wasn't traveling at the speed the team was expecting. Cosmic winds produced at or around the Eddington limit can flow as fast as 124 million miles per hour and even up to about 30% the speed of light.

The wind flowing from GX13+1, however, was travelling at a relatively leisurely 620,000 mph. We say relatively because that is still around 800 times as fast as the speed of sound on Earth. What the wind lacked in speed, however, it made up for with its density. However, unlike winds seen blowing from supermassive black holes near the Eddington limit, which are clumpy, the wind from GX13+1 flowed smoothly.

"It is still a surprise to me how 'slow' this wind is, as well as how thick it is. It’s like looking at the sun through a bank of fog rolling towards us. Everything goes dimmer when the fog is thick," Done added. "The winds were utterly different, but they're from systems which are about the same in terms of the Eddington limit.

"So if these winds really are just powered by radiation pressure, why are they different?"

Currently, Done and colleagues think these differences may be the result of temperature variations between the accretion disks around neutron stars like the one they observed and those surrounding supermassive black holes.

The accretion disks around supermassive black holes are larger and brighter than those around neutron stars, meaning their energy is dispersed over a larger area. This means the light emitted from these larger accretion disks is in the ultraviolet region of the electromagnetic spectrum, while the electromagnetic radiation from the disks around neutron stars is in the form of X-rays, which are higher in energy.

Ultraviolet light interacts with matter more easily than X-rays, so the team theorizes that radiation from supermassive black hole accretion disks may more effectively push matter, leading to faster winds.

This research could therefore reshape our understanding of how radiation and matter interact around some of the universe's most extreme accreting objects, and how they deliver energy to their wider surroundings, influencing evolving galaxies. The team's findings could also help guide future space telescopes such as NewAthena, an ESA mission set to launch in 2037 and designed to be the largest X-ray observatory ever built.

"The unprecedented resolution of XRISM allows us to investigate these objects — and many more — in far greater detail, paving the way for the next-generation, high-resolution X-ray telescope such as NewAthena," ESA Research Fellow Camille Diez said in the statement.

The team's research was published on Wednesday (Sept. 17) in the journal Nature.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Climate models are complex, just like the world they mirror. They simultaneously simulate the interacting, chaotic flow of Earth's atmosphere and oceans, and they run on the world's largest supercomputers.

Critiques of climate science, such as the report written for the Department of Energy by a panel in 2025, often point to this complexity to argue that these models are too uncertain to help us understand present-day warming or tell us anything useful about the future.

But the history of climate science tells a different story.

The earliest climate models made specific forecasts about global warming decades before those forecasts could be proved or disproved. And when the observations came in, the models were right. The forecasts weren't just predictions of global average warming – they also predicted geographical patterns of warming that we see today.

These early predictions starting in the 1960s emanated largely out of a single, somewhat obscure government laboratory outside Princeton, New Jersey: the Geophysical Fluid Dynamics Laboratory. And many of the discoveries bear the fingerprints of one particularly prescient and persistent climate modeler, Syukuro Manabe, who was awarded the 2021 Nobel Prize in physics for his work.

Manabe's models, based in the physics of the atmosphere and ocean, forecast the world we now see while also drawing a blueprint for today's climate models and their ability to simulate our large-scale climate. While models have limitations, it is this track record of success that gives us confidence in interpreting the changes we’re seeing now, as well as predicting changes to come.

Forecast No. 1: Global warming from CO2

Manabe's first assignment in the 1960s at the U.S. Weather Bureau, in a lab that would become the Geophysical Fluid Dynamics Laboratory, was to accurately model the greenhouse effect – to show how greenhouse gases trap radiant heat in Earth's atmosphere. Since the oceans would freeze over without the greenhouse effect, this was a key first step in building any kind of credible climate model.

To test his calculations, Manabe created a very simple climate model. It represented the global atmosphere as a single column of air and included key components of climate, such as incoming sunlight, convection from thunderstorms, and his greenhouse effect model.

Despite its simplicity, the model reproduced Earth's overall climate quite well. Moreover, it showed that doubling carbon dioxide concentrations in the atmosphere would cause the planet to warm by about 5.4 degrees Fahrenheit (3 degrees Celsius).

This estimate of Earth's climate sensitivity, published in 1967, has remained essentially unchanged in the many decades since and captures the overall magnitude of observed global warming. Right now the world is about halfway to doubling atmospheric carbon dioxide, and the global temperature has warmed by about 2.2 F (1.2 C) – right in the ballpark of what Manabe predicted.

Other greenhouses gases such as methane, as well as the ocean's delayed response to global warming, also affect temperature rise, but the overall conclusion is unchanged: Manabe got Earth's climate sensitivity about right.

Forecast No. 2: Stratospheric cooling

The surface and lower atmosphere in Manabe's single-column model warmed as carbon dioxide concentrations rose, but in what was a surprise at the time, the model's stratosphere actually cooled.

Temperatures in this upper region of the atmosphere, between roughly 7.5 and 31 miles (12 and 50 km) in altitude, are governed by a delicate balance between the absorption of ultraviolet sunlight by ozone and release of radiant heat by carbon dioxide. Increase the carbon dioxide, and the atmosphere traps more radiant heat near the surface but actually releases more radiant heat from the stratosphere, causing it to cool.

This cooling of the stratosphere has been detected over decades of satellite measurements and is a distinctive fingerprint of carbon dioxide-driven warming, as warming from other causes such as changes in sunlight or El Niño cycles do not yield stratospheric cooling.

Forecast No. 3: Arctic amplification

Manabe used his single-column model as the basis for a prototype quasi-global model, which simulated only a fraction of the globe. It also simulated only the upper 100 meters or so of the ocean and neglected the effects of ocean currents.

In 1975, Manabe published global warming simulations with this quasi-global model and again found stratospheric cooling. But he also made a new discovery – that the Arctic warms significantly more than the rest of the globe, by a factor of two to three times.

This "Arctic amplification" turns out to be a robust feature of global warming, occurring in present-day observations and subsequent simulations. A warming Arctic furthermore means a decline in Arctic sea ice, which has become one of the most visible and dramatic indicators of a changing climate.

Forecast No. 4: Land-ocean contrast

In the early 1970s, Manabe was also working to couple his atmospheric model to a first-of-its-kind dynamical model of the full world ocean built by oceanographer Kirk Bryan.

Around 1990, Manabe and Bryan used this coupled atmosphere-ocean model to simulate global warming over realistic continental geography, including the effects of the full ocean circulation. This led to a slew of insights, including the observation that land generally warms more than ocean, by a factor of about 1.5.

As with Arctic amplification, this land-ocean contrast can be seen in observed warming. It can also be explained from basic scientific principles and is roughly analogous to the way a dry surface, such as pavement, warms more than a moist surface, such as soil, on a hot, sunny day.

The contrast has consequences for land-dwellers like ourselves, as every degree of global warming will be amplified over land.

Forecast No. 5: Delayed Southern Ocean warming

Perhaps the biggest surprise from Manabe's models came from a region most of us rarely think about: the Southern Ocean.

This vast, remote body of water encircles Antarctica and has strong eastward winds whipping across it unimpeded, due to the absence of land masses in the southern midlatitudes. These winds continually draw up deep ocean waters to the surface.

Manabe and colleagues found that the Southern Ocean warmed very slowly when atmospheric carbon dioxide concentrations increased because the surface waters were continually being replenished by these upwelling abyssal waters, which hadn’t yet warmed.

This delayed Southern Ocean warming is also visible in the temperature observations.

What does all this add up to?

Looking back on Manabe's work more than half a century later, it's clear that even early climate models captured the broad strokes of global warming.

Manabe's models simulated these patterns decades before they were observed: Arctic Amplification was simulated in 1975 but only observed with confidence in 2009, while stratospheric cooling was simulated in 1967 but definitively observed only recently.

Climate models have their limitations, of course. For instance, they cannot predict regional climate change as well as people would like. But the fact that climate science, like any field, has significant unknowns should not blind us to what we do know.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Betelgeuse may have competition for the most exciting star about to go nova near Earth.

Astronomers have discovered the secret of a strange star system that has baffled them for years, finding it contains a dead star about to erupt after overfeeding on a stellar companion. The supernova explosion of this cosmic cannibal could be as bright as the moon, making it visible with the naked eye over Earth even in broad daylight.

The system in question is the double star V Sagittae located around 10,000 light-years from Earth, containing a white dwarf stellar remnant and its victim companion star, which orbit each other roughly twice every Earth day. The new research and the revelation of this white dwarf's imminent catastrophic fate answer questions about V Sagittae that have lingered for 123 years!

"V Sagittae is no ordinary star system - it's the brightest of its kind and has baffled experts since it was first discovered in 1902," team member and University of Southampton researcher Phil Charles said in a statement. "Our study shows that this extreme brightness is down to the white dwarf sucking the life out of its companion star, using the accreted matter to turn it into a blazing inferno.

"It's a process so intense that it's going thermonuclear on the white dwarf's surface, shining like a beacon in the night sky."

Final fate of a cosmic cannibal

White dwarfs represent the final stage of stars with masses around that of the sun, occurring when they run out of fuel for nuclear fusion. Indeed, our star will end its life as a cooling white dwarf when it runs out of hydrogen in around 5 billion to 6 billion years.

While this smoldering cosmic ember state represents the end for single stars going out with a whimper rather than a bang, white dwarfs that have a stellar companion can get a second lease on life and a more conclusive and explosive end. This happens when its dense stellar corpse is close enough to its companion star to allow its gravity to begin stripping away the partner's stellar material.

This material can't fall straight to the white dwarf because it has angular momentum, or spin. That means it forms a swirling, flattened cloud of matter around the white dwarf called an accretion disk, which gradually dumps matter to its surface.

This situation continues, and the stolen stellar material piles up on the surface of the white dwarf until it pushes this stellar remnant past the so-called Chandrasekhar limit of 1.4 solar masses. This is the mass limit that a stellar remnant has to exceed to trigger a supernova. The result is a Type Ia supernova that usually completely destroys the greedy white dwarf star.

However, this team found something very different and extraordinary happening with the stellar material being stolen by the white dwarf in V Sagittae.

The team uncovered the violent nature of V Sagittae using the Very Large Telescope (VLT), comprised of four individual telescopes located almost 9,000 feet (2,636 meters) on Cerro Paranal in the Atacama Desert of northern Chile.

This investigation revealed that there is a giant halo of gas comprised of material stolen from the companion star wrapped around both the cannibal white dwarf and its stellar victim. This is the result of the incredible amount of energy being generated in the system by the white dwarf as it strips material from its companion star.

This vast system-wide gas halo indicates that the white dwarf is snatching way more matter than it can handle. It also implies that this situation isn't going to continue for long, though when the end will come for this white dwarf isn't quite certain.

"The white dwarf cannot consume all the mass being transferred from its hot star twin, so it creates this bright cosmic ring," team member Pasi Hakala from the University of Turku said. "The speed at which this doomed stellar system is lurching wildly, likely due to the extreme brightness, is a frantic sign of its imminent, violent end."

"The matter accumulating on the white dwarf is likely to produce a nova outburst in the coming years, during which V Sagittae would become visible with the naked eye," Pablo Rodríguez-Gil from Spain’s Instituto de Astrofisica de Canarias said. "But when the two stars finally smash into each other and explode, this would be a supernova explosion so bright it'll be visible from Earth even in the daytime."

The team's research was published on Thursday (Sept. 11) in the journal Monthly Notices of the Royal Astronomical Society.